No Synthetic Due to Wear?

[BISCUT]

Statement was made on a Quad form that an engine couldne use synthetic (Rotella 5-40 in this instance) because his engine had some wear. Stated it would burn the synthetic but not the Rotella T version.

Granted the synthetic is 5-40 and the T version spoken of is 15-40. Is this true?? Or a myth? And so nobody gets their panties a bunched, I'm asking in general as it related to engines....not specifically dealing with a quad engine.

Am I wrong to think the amount of moly or addatives in general have more to do with it? Please, take me to school.

 

[JHZR2]

One classic wife's tale was that an engine couldntbe broken in on synthetic because it was to slippery, and thus would prevent break-in.

This is kind of like the opposite.

Personally, Ive changed to syn on engines as high as 160k miles, and never had an issue. Ive seen a few cases of seepage, but nothing else.

An engine is going to wear, syn or not. The logic as defined in your OP is that at some point, one must convert BACK from syn to regular oil, because the wear will have gotten to a point where syn can no longer be used...

 

[Quattro Pete]

Originally Posted By: BISCUT
Statement was made on a Quad form that an engine couldne use synthetic (Rotella 5-40 in this instance) because his engine had some wear. Stated it would burn the synthetic but not the Rotella T version.

That's incorrect.

The engine had some wear? What specifically does that mean? What is causing the wear? It surely isn't caused by moving from a 15w40 mineral to a 5w-40 synthetic oil.

 

[gathermewool]

Originally Posted By: Quattro Pete
Originally Posted By: BISCUT
Statement was made on a Quad form that an engine couldne use synthetic (Rotella 5-40 in this instance) because his engine had some wear. Stated it would burn the synthetic but not the Rotella T version.

That's incorrect.

The engine had some wear? What specifically does that mean? What is causing the wear? It surely isn't caused by moving from a 15w40 mineral to a 5w-40 synthetic oil.


+1 What was the poster using to qualify this statement? Excessive consumption? Tear down? UOA?

 

[mechtech2]

He probably was referring to the 5 and 15 first #s.
Move on .

 

[BISCUT]

Originally Posted By: mechtech2
He probably was referring to the 5 and 15 first #s.
Move on .


No Sir, I didn't want to get flamed for mentioning quad info when the question wasn't related to a quad per se. He had stated that on a few mud rides his air intake failed and let in some debris that caused his cylinder (V-twin) walls to be scratched.

My thought was same weight dino and synthetic shouldnt matter. But thats what I asked here...you guys are way more knowledgeable than I.

 

[friendly_jacek]

Originally Posted By: BISCUT

My thought was same weight dino and synthetic shouldnt matter. But thats what I asked here...you guys are way more knowledgeable than I.


It's not same weight. 15W40 usually has higher HTHS viscosity vs 5W40.

 

[Gokhan]

Originally Posted By: BISCUT
Statement was made on a Quad form that an engine couldne use synthetic (Rotella 5-40 in this instance) because his engine had some wear. Stated it would burn the synthetic but not the Rotella T version.

Granted the synthetic is 5-40 and the T version spoken of is 15-40. Is this true?? Or a myth? And so nobody gets their panties a bunched, I'm asking in general as it related to engines....not specifically dealing with a quad engine.

Am I wrong to think the amount of moly or addatives in general have more to do with it? Please, take me to school.

The amount of oil an engine burns strongly increases with decreasing viscosity. An engine that already has wear, especially at the valve-stem oil seals, will burn more oil with a thinner oil. 5W-40 is thinner than 15w40 (HTHS viscosity at least about 10% less) and it will burn more in an engine with worn valve-stem oil seals (or even with worn cylinder rings/linings).

But, no, if your engine doesn't already have wear, you won't see much difference in oil consumption with 5W-40, and chances are that you won't see much difference in wear over time with 5W-40 either.

Synthetic vs. conventional shouldn't make much difference but different oil brands and lines will have varying quality affecting engine wear and seal life. In general a conventional 15w40 should give you about the same oil life as a synthetic 5W-40 because a 15W- conventional oil has very low NOACK volatility (therefore cooks very slowly in use), not more than that of a synthetic 5W-. The only drawbacks of 15w40 are less fuel economy and difficult cold starting below freezing.