Synthetic oil misconceptions

[ippkiss]

There are a lot of misconceptions about Synthetic motor oils. I see some here on DSMtalk, and hear people talking about it elsewhere. Some of the stuff people come up with is just unbelievable.

This thread is not:

A place to make unsupported claims about oil. Please research and post a link to a website where you have found your information, so you are backed up.

Common misconceptions (other people feel free to ad to this list):


Does synthetic oil CAUSE oil leaks?
Links:


A: Motorhome magazine http://www.motorhomemagazine.com/output.cfm?ID=1175905

Answer:
Synthetic oil does not cause leaks. The only thing it will do is make any existing leaks (big or small) leak more because it penetrates better than conventional oil does- and it will make really small leaks more visible (a blessing in disguise?). So if your car has an oil leak, fix it before you switch, save yourself some money.

My daily driven 250k mile Honda civic has AMSOIL in it. There were a couple of small oil leaks in it when I got it, and they haven't gotten any bigger in the 10k mi of me driving on full synthetic AMSOIL.

Is synthetic oil thinner than conventional?

Answer: Modern motor oils (both synthetic and dyno) need to meet Auto manufacturer and SAE requirements for viscosity. 5W30 synthetic is 5W30. It is the same viscosity as 5W30 conventional. It has to be in order to have the SAE stamp of approval!

Can I switch to synthetic oil on an engine with high miles on it?
Links:
A: Mobil’s website http://www.mobiloil.com/USA-English/MotorOil/Car_Care/AskMobil/Switching_to_Synthetic_Motor_Oil_in_Higher_Mileage_Vehicles.aspx
B: Krane’s Synthetic Oil Bible http://www-d0.fnal.gov/~jkrane/cars/synth_survey.html

Answer:
Yes, you can definitely switch to synthetic motor oil in a high mileage engine. The only possible draw back is an increase in the SIZE of any existing oil leaks. Basically it makes small leaks more noticeable. It in no way “causes” leaks. If you have huge oil leaks, fix them before you switch to save yourself some money..

Can you use synthetic motor oil as a break in oil?

Answer:

I sell full synthetic, and I would not recommend it for break in. It has nothing to do with compatibility, rings seating, ect.

Its all about cost. When we break in a built motor, its started on the cheapest crap oil we can find (Walmart cheapo works well), the motor warms up and we change out the oil and filter. Then it depends on how anal you builder is. If it were my motor, I would do one again after 25 miles, 250 miles, 500 miles and again at 1000 mi to the Synthetic oil of choice. It seems stupid to risk a built motor over a couple of dollars worth of oil. There are tons of crap in your oil when breaking in a motor, and you want to get that crap out as quickly as possible by changing the oil alot.


Switching back and forth:
Quote: I've heard once you use synthetic oil that you can't switch back to conventional oil. true/false?

Answer: false.
You can switch back and forth all you want. You can also mix them if you want.


I would like to invite anyone to ask questions, and comment on this.


There are manufactures our there calling group III hydro cracked oil a "synthetic". Beware of what you put in your car based on hype. Why do I like AMSOIL so much? Because out of all the manufactures they push used oil analysis to actually determine when its the right time to change your oil.

[740 Turbo Brick]

Some very good information in here, most of which I didnt know before.

If your car burned a slight amount of oil through the valve seals, what would happen if you switch to syn? Because it penetrates more would it coat the seals and "revive" them a little or would it just go right past them more so than it would with conventional oil?

[flexnuts02]

It would most likely just burn more oil.

[Don Boosted]

It would most likely just burn more oil.

I hope AMSoil tells you you are perpetuating common misconceptions :P:D

[ippkiss]

It would most likely just burn more oil.

I agree 100%. AMSOIL is not restore, nor does it claim to be. It is not a "compression in a can" type of product.

If the car is burning oil through the valve seals, the only thing that is going to fix that problem is doing it right and having the seals redone.

[MyBoostedGST]

There are SO many misconceptions out there about synthetic oil. Working at a quick lube, I hear so many you could not believe.

Only thing I am questioning about the list, is about breaking the motor in. I have always been told that you should only use regular conventional oil (NON-synthetic) because it allows more friction in the engine, causing parts (AKA...Rings/etc...) to seat faster. I have always been told change the oil after first 15 mins idling, then after 50 miles, and then again after 500 miles. At the 500 mile change, is when you should switch to whatever oil you will be using for the life of the engine.

Otherwise, everything else is true. One thing I do have to say though, is unless the car is under strict warranty, do NOT go more than 3k miles per oil change if you are using conventional oil. (I wouldn't even suggest it on synthetic oil, although many companies claim you can). I see Honda's with 50k miles on them only a year or two old, who are already burning anywhere between a half quart and a full quart every oil change. That is because the owners are using basic oil and running anywhere between 4.5k and 5.5k, but that is within the range that Honda recommends.

[ippkiss]

There are SO many misconceptions out there about synthetic oil. Working at a quick lube, I hear so many you could not believe.

Only thing I am questioning about the list, is about breaking the motor in. I have always been told that you should only use regular conventional oil (NON-synthetic) because it allows more friction in the engine, causing parts (AKA...Rings/etc...) to seat faster. I have always been told change the oil after first 15 mins idling, then after 50 miles, and then again after 500 miles. At the 500 mile change, is when you should switch to whatever oil you will be using for the life of the engine.

Otherwise, everything else is true. One thing I do have to say though, is unless the car is under strict warranty, do NOT go more than 3k miles per oil change if you are using conventional oil. (I wouldn't even suggest it on synthetic oil, although many companies claim you can). I see Honda's with 50k miles on them only a year or two old, who are already burning anywhere between a half quart and a full quart every oil change. That is because the owners are using basic oil and running anywhere between 4.5k and 5.5k, but that is within the range that Honda recommends.



I'm with you, I don't know if I was unclear about what I stated above but: I sell full synthetic, and I would not recommend it for break in. It has nothing to do with compatibility, rings seating, ect.

Its all about cost. When we break in a built motor, its started on the cheapest crap oil we can find (Walmart cheapo works well), the motor warms up and we change out the oil and filter. Then it depends on how anal you builder is. If it were my motor, I would do one again after 25 miles, 250 miles, 500 miles and again at 1000 mi to the Synthetic oil of choice. It seems stupid to risk a built motor over a couple of dollars worth of oil. There are tons of crap in your oil when breaking in a motor, and you want to get that crap out as quickly as possible by changing the oil alot.

I was recommending that you use cheap dyno oil until the oil change at 1000 mi and switching to the oil of choice at that point.

[MyBoostedGST]

I understand what you are saying, but what I am saying, is that the reason to use cheap oil is not the cost, but that synthetic oil is not good for the motor at the startup.

The way you were making it sound, is that if you had money to just piss away, then it would be fine to use synthetic oil for the first oil changes. What I have heard, is that even without regards to cost, conventional oil is BETTER for break-in on a motor. Like I said, it's what I have always heard. Just wanted to make that clear.

[ippkiss]

Honestly I've heard both ways from motor builders. Some could care less, and some were nuts about it.

From my understanding, alot of new cars some with synthetic in them now and they use that just fine for brake in. If it were me, I would use dyno oil for the break in, but in the end I think its something for your engine builder and you to talk about and decide on. . I hear it can also depend on the type of ring that is used in the build as well.

[dtowneclipse]

Alot of people dont understand why switching to synthetic will make small leaks possible bigger, or even cause new leaks....the reason being is that with conventional you get a certain amount of buildup or "Gunk" that accumulates over time, somewhat effectively slowing down leaks or even plugging them. Once synthetic oil is ran is these engines, the synthetic actually washes alot of this gunk away, unclogging or unplugging these leaks.

[pdsd16]

Switching back and forth:
Quote: I've heard once you use synthetic oil that you can't switch back to conventional oil. true/false?

Answer: false.
You can switch back and forth all you want. You can also mix them if you want.


I would like to invite anyone to ask questions, and comment on this.





I've been using full synthetic oil for the last couple of oil changes. I did it through the dealer and when I made the switch from a blend to full synthetic they said they had to completely drain the engine or do something different than what is normally done in a normal oil change. I am now about ready to do my first oil change myself, but I bought conventional oil instead of full synthetic. Should I return the conventional oil and go back to full synthetic? If I do stick with conventional do I have to do anythnig special in this oil change?

[16G_tsi_awd]

Think what you guys want to think. I don't need links to prove. I tear engines down and look for myself. It causes premature bearing failure. Notice all the guys spinning journal bearing turbo's and useing synthetic burn their bearings up. I am very meticulous about shit. As are a lot of you guys. I know when I tear down a motor using synthetic I cannot get the residue off the internal parts. Especially the porous aluminum castings. I have also saw a ton of rod bearing failures more often then not using synthetic.

I use conventional rotella T in a cat diesel for a million miles tear it down and see almost zero wear on the piston side walls. The main bearings are always wore more closer to the trans you get. And they are all worn on the same side getting less and less the closer you get to the front. Unless a unbalanced dampener is being used. If your dampener wobbles I can guarantee you have more wear on the front main then is normal. Most the time I can can just roll a set of bearings in a cat without even removing the crank and send it on it's way. And if a diesel has to much blow by guess what happens. They suck the oil up threw the oil and start to run on oil. Then the only way you can shut them off is cover the intake. If you can't cover the intake guess what happens? :blowingup:

This being said and I could say a lot more but I don't need to. Amsoil is by far the best synthetic I have came across. I don't know why accept for the thought that maybe it is not synthetic or a blend but it always shows good results. I throw my bearings in the scrap pile but maybe a diesel technician on here can help us out. Get a cat that goes 1 million miles on synthetic and changes his oil exactly when he should. Put the main bearings all in a row then do the same for a guy using shell rotella T right next to them and you will see for yourself. Don't use amsoil either. It is dyno oil in disguise! :P

[twinturbo3k]

So, wait, you are saying fossil oil is better for rod bearing life?

I spun a bearing in one of my cars, and I was using conventional oil... Pennzoil to be exact and it was at proper levels with no dents in the pan.

I have yet to have any bearing failure using Royal Purple, or any problems lubrication related like lifter tap, etc. I've also run my old 160,000 mile bottom end Galant 25-27PSI and had absolutely no issues using synthetic, bearing wise. I had a little bit of blow by which made my oil pan leak a bit, so, while resealing the pan I took a look at my bearings and they were in suprisingly good shape- they showed next to no wear.

[Sebba]

Think what you guys want to think. I don't need links to prove. I tear engines down and look for myself. It causes premature bearing failure. Notice all the guys spinning journal bearing turbo's and useing synthetic burn their bearings up. I am very meticulous about shit. As are a lot of you guys. I know when I tear down a motor using synthetic I cannot get the residue off the internal parts. Especially the porous aluminum castings. I have also saw a ton of rod bearing failures more often then not using synthetic.

I use conventional rotella T in a cat diesel for a million miles tear it down and see almost zero wear on the piston side walls. The main bearings are always wore more closer to the trans you get. And they are all worn on the same side getting less and less the closer you get to the front. Unless a unbalanced dampener is being used. If your dampener wobbles I can guarantee you have more wear on the front main then is normal. Most the time I can can just roll a set of bearings in a cat without even removing the crank and send it on it's way. And if a diesel has to much blow by guess what happens. They suck the oil up threw the oil and start to run on oil. Then the only way you can shut them off is cover the intake. If you can't cover the intake guess what happens? :blowingup:

This being said and I could say a lot more but I don't need to. Amsoil is by far the best synthetic I have came across. I don't know why accept for the thought that maybe it is not synthetic or a blend but it always shows good results. I throw my bearings in the scrap pile but maybe a diesel technician on here can help us out. Get a cat that goes 1 million miles on synthetic and changes his oil exactly when he should. Put the main bearings all in a row then do the same for a guy using shell rotella T right next to them and you will see for yourself. Don't use amsoil either. It is dyno oil in disguise! :P

Unfortunately, you can't make a statement like that based on that data.

[ippkiss]

I've been using full synthetic oil for the last couple of oil changes. I did it through the dealer and when I made the switch from a blend to full synthetic they said they had to completely drain the engine or do something different than what is normally done in a normal oil change. I am now about ready to do my first oil change myself, but I bought conventional oil instead of full synthetic. Should I return the conventional oil and go back to full synthetic? If I do stick with conventional do I have to do anythnig special in this oil change?

They probable meant that they would actually let the car sit for a while and drain all the way, because most dealers and lube places do not let your car sit for long time to get all the old oil out, the drain it and fill it as quick as possible.

I'm not going to sit here and say that your motors going to explode unless you run a synthetic. Cars do run fine on normal oil, and I have run the cheap walmart oil in my beater cars before. I run Amsoil in all of my cars now just because I was never that great about upkeep on some of my beaters and went more than the recommended 3000 mi on conventional oil. I would rather pay 2x what walmart oil costs, and get 9000 mi on an oil change because that gives me more time with my family, or working at the shop.

Your fine on switching to conventional oil if you want to. The only thing I recommend when do your own oil change is let your car sit for a while with the drain plug out and oil filter off so you get as much of the old oil out as you can. I do this for all of my cars for every oil change. I'll go do something else for a while once I've got the filter off and the drain plug out.

[16G_tsi_awd]

So, wait, you are saying fossil oil is better for rod bearing life?

I spun a bearing in one of my cars, and I was using conventional oil... Pennzoil to be exact and it was at proper levels with no dents in the pan.

I have yet to have any bearing failure using Royal Purple, or any problems lubrication related like lifter tap, etc. I've also run my old 160,000 mile bottom end Galant 25-27PSI and had absolutely no issues using synthetic, bearing wise. I had a little bit of blow by which made my oil pan leak a bit, so, while resealing the pan I took a look at my bearings and they were in suprisingly good shape- they showed next to no wear.

Pennzoil is the worst of all conventional oils. It uses wax and creates build up going from hot to cold.

[740 Turbo Brick]

Wow. Thanks for the heads up there. I occasionally use pennzoil.

Have any info on Valvoline High milage - 75,000 + miles? It says it has seals additives to help higher milage engines. I usually either use that or Castrol Syn blend

[pdsd16]

They probable meant that they would actually let the car sit for a while and drain all the way, because most dealers and lube places do not let your car sit for long time to get all the old oil out, the drain it and fill it as quick as possible.

I'm not going to sit here and say that your motors going to explode unless you run a synthetic. Cars do run fine on normal oil, and I have run the cheap walmart oil in my beater cars before. I run Amsoil in all of my cars now just because I was never that great about upkeep on some of my beaters and went more than the recommended 3000 mi on conventional oil. I would rather pay 2x what walmart oil costs, and get 9000 mi on an oil change because that gives me more time with my family, or working at the shop.

Your fine on switching to conventional oil if you want to. The only thing I recommend when do your own oil change is let your car sit for a while with the drain plug out and oil filter off so you get as much of the old oil out as you can. I do this for all of my cars for every oil change. I'll go do something else for a while once I've got the filter off and the drain plug out.


Thanks a ton for the information.

[Seanaynay25]

What is the benefit from lets say Mobil 1 Synthetic, opposed to some of that Royal Purple?

[braceyoself777]

Switching between the oils is the biggest myth I believe. If the oils are the same weight, then there should be no problem. Good info! My first post cause everything locked for me.:confused:

[pboglio]

I used conventional oil on my 91 GS Turbo and within 56,000 miles the engine had some terrible leakdown results. My 97 GSX with 115,000 miles is showing 179 psi compression across the board, and an average of 3-4% leakage on all cylinders. This is with the same lazy 6,000 mile change intervals I used on my other DSM. I attribute the motors extremely good health to using synthetic. I run 10w30 as the thinner stuff I don't feel comfortable with. So far great results.

[ippkiss]

What is the benefit from lets say Mobil 1 Synthetic, opposed to some of that Royal Purple?

Royal Purple, Redline, Amsoil (and others) all used the finest base stocks to make the best oils. If you believe what the rumors say, Mobile 1 is not a true synthetic oil anymore.

I personally stay away from any "blend" because usually when its a blend all they have to give you is 1% synthetic, 99% conventional oil. I'm willing to bet even Amsoil is the same way.

[16G_tsi_awd]

I used conventional oil on my 91 GS Turbo and within 56,000 miles the engine had some terrible leakdown results. My 97 GSX with 115,000 miles is showing 179 psi compression across the board, and an average of 3-4% leakage on all cylinders. This is with the same lazy 6,000 mile change intervals I used on my other DSM. I attribute the motors extremely good health to using synthetic. I run 10w30 as the thinner stuff I don't feel comfortable with. So far great results.

Leakdown test proves nothing of oil. That's the valve seats and valves your talking about. Compression test on the other hand would be another story.

[pboglio]

Leakdown test proves nothing of oil. That's the valve seats and valves your talking about. Compression test on the other hand would be another story.

Care to go into more detail?

I personally disagree. A leak down will pick up worn or improperly seated piston rings, valves, valve guides, head gasket leak or what have you. I think the pros/cons of either can be argued. Compression tests will get some oil flow to the cylinder walls due to cranking which would help seal the rings, where the leak down test will be pressurizing dry with the piston and ring pack static. On the other hand, a compression test can be falsed by a high amount of carbon build up on the piston top, a leakdown test would be less affected. They are tools, I used them in combination.

About what you mentioned about bearing wear with synthetic, that sounds unusual. Synthetic has more shear resistance than standard oil and I can't see it causing more bearing wear.

[944G37]

Our shop deals this stuff. I wouldn't run anything else if i had a choice. I am a firm believer in the synthetic oils myself. Ive seen claim from them that they have run their oil 80k in an engine. We run our diesel trucks at 1 year intervals with it. http://www.sentinelsynthetic.com/english/product.htm

[pboglio]

When I made the switch to synthetic, the car felt a touch easier to rev. The cold startups in winter were a huge difference over dino oil. I just pulled off my T28 with 65,000 miles on the clock and thanks to the synthetic it spins fine with normal radial play. Camshaft lobe wear looks great as well even after 30,000 miles. Valvoline Syntec synthetic 10w30 is what I run. I've been looking to try Royal Purple but just haven't been motivated enough to make the switch. The thing I notice the most about synthetic is how "sticky" it is in contrast to standard oil.