Oil and Engine Design...PAO vs Ester Oils

[FullNelson]

So lately Ive been digging more and more into this oil stuff and came up with a few questions.

ill start off with digging up an old thread
http://www.supramania.com/forums/showthread.php?t=45452

In the 4th post you mention this:

Thinking of a thicker oil as insurance is a very common misconception. In a 7M, the bearings were *designed* to use a viscosity in the 10-11 cst viscosity range at ops temp.

How so are the bearings designed for that range? Is it the clearances of the bearings, or is it maybe a metalurgy thing?

If it is clearances, which I suspect it is, how do you know when your clearances are tight enough to dictate uing a lighter weight like a 5w-20? Just taking a jab at this, but would you want to use the lightest weight oil that would still give you good oil pressure? If so, where would you draw the line on too low of an oil pressure in the sake of trying to use a thinner oil?



Part two. :biglaugh:

So in the same thread, you were mentioning that the Redline ester based oils were top notch, and it was percieved that you had a slight preferance for them over the amsoil PAO base.http://www.upmpg.com/tech_articles/motoroil_viscosity/

Group V (5) based synthetics are usually not compatible with petroleum or petroleum fuels and have poor seal swell.

Lol and we know that as mk3 owners, were allready fighting an uphill battle on leaks and smoking motors as it is.
So the question is would you reccomend a PAO base over and ester base for our motors? Or does Redline, and Royal Purple ester base oils contain enough of a PAO mix in them in keep the seals and 'conditioned'?



And lastly, what is the differences between the "regular" and "racing" oils? most of the Racing oils are about on par with the Regular oils, an in some case do a worse job on the 4 ball test. Wheres the differences?


Sorry for all the questions, It seems the more I learn stuff the more I realize I know even less. :aigo:

-Bryan

 

[jdub]

So lately I’ve been digging more and more into this oil stuff and came up with a few questions.

I’ll start off with digging up an old thread
http://www.supramania.com/forums/showthread.php?t=45452

In the 4th post you mention this:

How so are the bearings designed for that range? Is it the clearances of the bearings, or is it maybe a metallurgy thing?

If it is clearances, which I suspect it is, how do you know when your clearances are tight enough to dictate using a lighter weight like a 5w-20? Just taking a jab at this, but would you want to use the lightest weight oil that would still give you good oil pressure? If so, where would you draw the line on too low of an oil pressure in the sake of trying to use a thinner oil?

It’s actually both

However, clearances play the major role along with the overall characteristics of the engine. You are limited by the TSRM bearing clearances, in the case of a 5W-20, on the min spec. The long crankshaft and its tendency to flex also plays a role. Additionally, stock 7M piston clearances will allow excessive blowby with oil that’s too thin affecting the volumetric efficiency of the engine.

Clearances can be opened up to accommodate the reduced flow thicker oil will cause…other modifications to the oil system will be required to insure reliability. IJ has proved this in practice.

The modifications to safely use thinner oil is more difficult. Bringing the bearing clearances down to min spec is the easy part. What is not easy is stopping crank flex to prevent bearing wear (IJ saw it along the bearing edges). And, machining piston-to-wall clearances down to a value that will prevent blowby…you will have to use ceramic coated piston tops to prevent excessive expansion that will lock the motor up.

You can use a 5W-20…JJ did it for a while, but his motor is meticulously maintained. I’ve also seen a case where it caused pressure problems. What you are looking for is 10 psi of oil pressure per 1000 RPM…on the 7M-GTE, the oil squirters are a pressure bleed. Even worse is the oil cooler circuit relief valve that essentially limits pressure to it opening spec of ~40 psi.

I like the idea of using thinner oil to increase fuel economy and flow through the engine, but it can be over done IMO on the 7M. The 0W & 5W-30 oils out there will work almost as well in this regard and provide the pressure the engine requires.

Part two.

So in the same thread, you were mentioning that the Redline ester based oils were top notch, and it was perceived that you had a slight preference for them over the Amsoil PAO base.http://www.upmpg.com/tech_articles/motoroil_viscosity/

LOL and we know that as mk3 owners, were already fighting an uphill battle on leaks and smoking motors as it is.
So the question is would you recommend a PAO base over an ester base for our motors? Or does Red Line, and Royal Purple ester base oils contain enough of a PAO mix in them in keep the seals and 'conditioned'?

Ester based oil are the best (especially for thermal stability)…that’s why they are used in jet engines

Properties of esters:
- Typically a very polar molecule, that is, they are attracted to metal due to their electrical charge.
- Excellent solvency
- High thermal stability

These characteristics make ester a near ideal lubricant, the caveat is they must be formulated properly. It also makes ester a very useful additive, especially in a polar-neutral base like PAO. Not so in oils if the ester electric charge is greater than the anti-wear additive…the ester can cause greater wear.

The Amsoil article is wrong. Pure PAO causes engine seals to contract…the result was the problem with leaking seals in the early formulation of PAO oils. Ester causes seals to swell…every PAO based oil (including Amsoil) uses ester (primarily diester) as a seal conditioner additive precisely for this reason. Diester’s solvency is excellent in PAO. An added plus is diester is a very good VI improver, reducing the base oils pour point and cold flow viscosity.

One thing to keep in mind, both PAO and ester are very good engine cleaning agents. Old seals that have hardened may have deposits as the only thing keeping the seal from leaking. If you use a PAO or ester based oil, you can get a leak due to their ability to dissolve these deposits. The leak you sometimes see when switching to a synthetic oil is not due to the oil itself, it’s due to bad seals.

To clear your confusion, Red Line is an ester (Grp V) base stock…from what I can glean primarily polyol ester and complex esters blended with other additives, in particular anti-oxidants. Royal Purple is a PAO base stock oil…like other Grp IV oils, it contains a relatively small percentage of ester as a seal conditioner. Castrol European Formula 0W-30 (aka German Castrol), Shell Helix, Pentosin (VW and Audi), Neo, and Eneos are PAO based oils as well. Motul and VP oils are ester based.

I favor the PAO oils (I use German Castrol), they are better suited for the 7M and JZ series engines IMO. #1) they are less expensive, and #2) an automotive engine doesn’t require the capability ester based oil provides…initial thermal degradation for diester is 275 deg C and for polyol ester is 315 deg C. Way above the temps a car engine would ever produce. Plus, the ester oils are more difficult to formulate properly due to ester’s high polarity. Red Line does a good formulation job, but there are motors where Red Line increased the percentage of wear metals in certain engines. I suspect that is due to the metals used in the bearings…ester dissolves zinc oxides and is incompatible with lead.

And lastly, what is the difference between the "regular" and "racing" oils? Most of the Racing oils are about on par with the Regular oils, an in some case do a worse job on the 4 ball test. Where’s the differences?

It’s the additive pack. Racing oils do not contain near the amount of additives you will see in oil meant for street use and this includes anti-wear additives. The reason? On a race car, the oil is changed every race and the motor is rebuilt every 2-3 races.

It’s a common misconception that racing products are “better’”. In the case of motor oil, this is not true…that is unless you are running a race car.

Sorry for all the questions, it seems the more I learn stuff the more I realize I know even less.

-Bryan

NP…Join the club
Gets worse the older you get too.

 

[FullNelson]

With the PAO oils using diester as an additive and being a VI, relatively how much is does it lower the sheer resistance?

When you say Ij opened up his clearances, I’m guessing to say that this was meaning he opened them up from a very tight tolerance. Any idea how severe it was opened, Maybe to the clearances that us mortal men can get from our machine shops, or to the clearances you’ll see from the 200k mile motors out there?

I’ve gotten word from my machinist that I should be around 90 psi; I don’t have the details on that yet, but for arguments sake ill say it’s with maybe a 65 cSt viscosity 10W-30, at 3000 RPM. Does this sound about on par? And I’m not sure but from the beginning he was against shimming the oil pump RV, So I want to know where he’s getting these numbers lol.


So when switching to a synthetic it can show what seals are hard and brittle, but if you have new seals and start off with good PAO oil, will it do anything in the way of conditioning the seals, and prolonging the life? Or is it just going to make it more pronounced when the seals go out?

You would think that for a race oil with less additives, and seemingly less function would cost as much, if not more for a street oil.

One last one, Ive read that its recommended for an oil analysis to be taken every 2000 miles. Is this usually a short enough time frame for most to detect those signs of extreme bearing wear (Rod knock) of coolant in the oil (BHG)?

Lol I think I’m gonna just have to find a college class on this; I can’t seem to run out of questions.
BTW thanks for the title, I could not think of anything direct to title it. Guess this is why you’re paid the big bucks!

 

[jdub]

With the PAO oils using diester as an additive and being a VI, relatively how much is does it lower the sheer resistance?

Ester is more shear stable than PAO.

When you say Ij opened up his clearances, I’m guessing to say that this was meaning he opened them up from a very tight tolerance. Any idea how severe it was opened, Maybe to the clearances that us mortal men can get from our machine shops, or to the clearances you’ll see from the 200k mile motors out there?

Well, iirc it was right at TSRM max spec...you'll need to ask IJ. I do know he used a brand new block...plus, his oil system is heavily modified. Way more than most.

I’ve gotten word from my machinist that I should be around 90 psi; I don’t have the details on that yet, but for arguments sake ill say it’s with maybe a 65 cSt viscosity 10W-30, at 3000 RPM. Does this sound about on par? And I’m not sure but from the beginning he was against shimming the oil pump RV, So I want to know where he’s getting these numbers lol.

Does that sound like 10 psi per 1000 RPM? Sounds like he's pulling it out of where the sun never shines

There is no 65 cst 10W-30 oil on the planet at ops temp (100 deg C). Cold yes, hot no...while you may get higher pressure cold, it's not going to last and therefore will not meet the 10 psi per 1000 RPM test cold. You have to look at pressure hot.

So when switching to a synthetic it can show what seals are hard and brittle, but if you have new seals and start off with good PAO oil, will it do anything in the way of conditioning the seals, and prolonging the life? Or is it just going to make it more pronounced when the seals go out?

Come on man...think! Didn't I say ester was a good seal conditioner and that's why you see it added to PAO oils?

You would think that for a race oil with less additives, and seemingly less function would cost as much, if not more for a street oil.

Don't know, don't care...a racing oil has no business in a street machine IMO.

One last one, Ive read that its recommended for an oil analysis to be taken every 2000 miles. Is this usually a short enough time frame for most to detect those signs of extreme bearing wear (Rod knock) of coolant in the oil (BHG)?

You heard wrong...you should do analysis every 4000 miles on a good motor. If you are having wear metal, dilution, or contamination issues, I can see doing it at 2500 miles or so.

Lol I think I’m gonna just have to find a college class on this; I can’t seem to run out of questions.
BTW thanks for the title, I could not think of anything direct to title it. Guess this is why you’re paid the big bucks!

Might want to read Dr Haas in my sig and more of the threads here. Absorb the material and think before you ask.

 

[QuebecmkIII]

It’s actually both
One thing to keep in mind, both PAO and ester are very good engine cleaning agents. Old seals that have hardened may have deposits as the only thing keeping the seal from leaking. If you use a PAO or ester based oil, you can get a leak due to their ability to dissolve these deposits. The leak you sometimes see when switching to a synthetic oil is not due to the oil itself, it’s due to bad seals.

If I understood, for the majority of the old engine like mine with 120 milles on it, it's a bad idea to switch synthetic or a beautiful blue cloud will appear in the back mirror when the engine comes alive...
I'm condemned to use a pure mineral oil, If I take a look on the penzoil platinum, a mineral oil(group III) with synthetic additive, the problem is the same...(Cleans out up to 46% of engine sludge)
http://www.pennzoil.com/products.html#Platinum
sad, i wanted the best for my GTE

 

[jdub]

Not true...PAO or ester oils will have no effect on the ability of the rings to seal. The blue cloud is due to worn rings or bad valve seals, not the oil.

It is true (with worn rings) that switching to a thinner oil (conv or syn) will allow more oil to be forced past the rings into the combustion chamber...that will produce the cloud you speak of. At that point, or with worn bearings, using a thicker oil will not hurt...the damage is already done

 

[Poodles]

Or, in the case of valve stem seals that are being barely held together with deposits...

Most of what you hear about synthetics are holdovers from when they first came on the market. Modern synthetics are leaps and bounds better and any issues have been worked out...

 

[Doward]

I'm a fan of ester-based oils (Redline specifically) and I plan on doing a full oil analysis for the life of my 7M.

Eventually, I'd like to be running Redline oil on 15-20k oil rotations (using a bypass filter with some good old Scot single ply )

 

[Nick M]

If I understood, for the majority of the old engine like mine with 120 milles on it, it's a bad idea to switch synthetic or a beautiful blue cloud will appear in the back mirror when the engine comes alive...
I'm condemned to use a pure mineral oil, If I take a look on the penzoil platinum, a mineral oil(group III) with synthetic additive, the problem is the same...(Cleans out up to 46% of engine sludge)
http://www.pennzoil.com/products.html#Platinum
sad, i wanted the best for my GTE

The old product question was already addressed. So I will add that Penzoil makes very good conventional oils. Despite what the retards at say Jiffy Lube or Wal Mart might say. I don't know. Maybe your local "lube tech" has learned differently. And if you can find it, Penzoil Pure Base is another very good conventional oil. But it may just be a relable of the Platinum oil.

 

[sneakypete]

I'm a fan of ester-based oils (Redline specifically) and I plan on doing a full oil analysis for the life of my 7M.

Eventually, I'd like to be running Redline oil on 15-20k oil rotations (using a bypass filter with some good old Scot single ply )

im on the same boat as you. been running redline for about 3000 miles so far with a conventional and bypass filter. that bypass filter does a great job. the oil looks pretty much the same as when i poured it in. im due for an analysis soon and cant wait for the results.
dont plan on changing the oil until 10k miles

-pete