Synthetics and Leaks

[TallPaul]

If I understand correctly, modern synthetics don't cause leaks, but can make existing leaks or seeps worse and/or can clean off a false seal, causing a leak.

So, the question is, which synthetic is more likely to do that:

Group III such as Castrol Syntec
Group IV such as Mobil 1
Group V such as Redline

I am guessing that as group number goes up, the likelihood of worsening an existing leak increases, and that Group III is about as safe as running a Group I or II conventional.

 

[Curious Kid]

Good question, though there are a lot of compounds to compare.

If such the case, I suppose one could also say that as one moves away from using the comparatively less refined base oils that had a natural tendency to swell seals, these same seals would then relax. The unfortunate thing is that these seals would have worn-in in their swelled state, and any laxing could create clearences that enable the passing of oil.

This reminds me of an article I read that said that the changing of the oil formulation in equipment may even require the changing of seals. I wonder if this is part of the reasoning for such a statement other than compatability issues with the previous oil that has penetrated into the seal material.

 

[TallPaul]

Hmmm, let's revise the list then:

Group III such as NAPA Syntec
Group IV such as Mobil 1
Group V such as Redline

I have run up to a quart of Redline in an engine that has seepage around the seals with on bad effect, unless that is why it is seeping, but no drips.

 

[SSDude]

I suspect that the group V would be best at cleaning because of the esters.

 

[JAG]

Redline motor oil and transmission oil leaked in my last car, a new 02 Suburu Impreza RS. The motor oil burned at double the normal rate but gear oil actually dripped out past the output shaft seals. Oils with mostly ester basestocks oils are the ones you have to really be careful of with leaks due to seal incompatibility. I'm sure other oils (like Mobil 1, Amsoil, etc) are capable of springing a leak in some old, cruddy engines, but it seems pretty rare. Most oils that are sold meet seal compatibility tests (I don't think Redline does). It seems that leaks can occur from seal incompatibility, too low viscosity of an oil, and removal of false seals on an old engine (esters may enhance this due to cleaning action but so does strong detergents in additive package). I wouldn't be surprised if a Group II diesel/gas oil cleans seals more than a gas-only Group III oil.

 

[Ramblin Fever]

What are some examples of oils with ester's?

Some without?

 

[TallPaul]

A lot of oils might have a bit of ester, but few have a large part of the base oil in ester. I am not concerned about those with a little bit. Redline probably is half ester. That is pretty high. I think Motul gets higher.

 

[sky jumper]

hmm. I thought Mobil had to add grp V content to M1 in order to prevent the leaks???

 

[JAG]

Yeah, Redline and Motul are the heavy ester formulators I can think of. There are others in the world, but they aren't commonly found in the U.S.

 

[Alex P.]

I leaked M1 in a 305 that otherwise didn't lose a drop of Syntec. But both are fully formulated oils, so it's not much of a Group vs Group observation.

 

[vwoom]

In my 190E, I ran Grp III(Synpower 10w30)last spring and it didn't leak any worse than running Grp II+ Delo 15w40, considering it was thicker than the former.

In fact I got more drips with Delo. I assume due to the marked increased in oil psi...it just zooms up there quicker and higher than Synpower.

 

[Jimbo]

Syntec is not a safe choice in this regard. I tried 10W-40 Syntec in place of 15w40 Delo for one interval and it did find places to seep out where the Delo did not. Syntec is not just straight Group III, but a blend with esters. Seal shrinkage is not the issue, I think it is lower viscosity at any temperature below 100C.

 

[TallPaul]

I'm going to guess that Group III won't make an engine that has seeps leak, but PAO and ester might. Or is it possible that a higher grade Group III that is very PAO like would also potentially turn a seep into a leak?

 

[Ramblin Fever]

How is the Rotella synthetic classified?

 

[bkrell]

Rotella is a group III, I believe.

 

[MGBV8]

Quote from Motul Interview
A synthetic will find a leak A vegetable synthetic has a property we call unctuousness or oiliness.. It is polarized and actually has a negative end chain and iron and steel have a positive end chain. What happens is that the oil is attracted to bare surfaces and is trying to spread to wherever there isn't any oil. Thus if you have a weak gasket, a good synthetic oil will capillary or migrate through a weak gasket.

 

[vwoom]

In my 190E, I ran Grp III(Synpower 10w30)last spring and it didn't leak any worse than running Grp II+ Delo 15w40, considering it was thicker than the former.

In fact I got more drips with Delo. I assume due to the marked increased in oil psi...it just zooms up there quicker and higher than Synpower.

I'll be running a thicker PAO xw40 mix of 4:1 M1 EP 15w50:M1 0w20 come next oci..n see what happens.