longitudinal oil studies?

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Have any unbiased longitudinal studies been performed on the cost-benefits of synthetic oils versus premium non-synthetic motor oils? I'm trying to justify why I would pay up to 3X more for a product and would like to see an unbiased objective study over time.

thanks, Pat
 
"longitudinal" - big word. By inspection, the primary benefit of synthetic oils are long OCI's, not greatly reduced wear or extended engine life. So maybe if you factor in labor cost or opportunity cost of you time, you can justify it by having fewer changes. Otherwise why would someone put a lot of effort to document what is obvious?
 
There are no motor oil studies that answer the question. All we can do is go by the numbers we find in the numberous UOA's we see on sites like this.

My own experience suggests a cheap synthetic lasts much longer than a conventional oil and when I factor in the cost of labour, it is most cost effective to use a cheap group III synthetic and run the oil 10,000 plus.

The choice is yours.
 
Syn oil has certain benefits,if you use the benefits, then syn oils are worth the price.
 
http://www.bobistheoilguy.com/used-oil-analysis-how-to-decide-what-is-normal/

Its on the home page. Very good article, and I think the only actual evidence I've seen on this question.

IIRC the micro analysis example, (IIRC there's no relevant macro-analysis example) which I take to be a longitudinal study, found no significant benefit from synthetic oil at a 5K OCI.

One might reflect on WHY there isn't more evidence available (assuming there isn't).

It wouldn't be hard for an oil company to sponsor, say, the DHL delivery fleet and get loads of data on the operational difference between running a synthetic and a mineral oil, but if they have, AFAIK they've kept it quiet.

Could it be that facts and marketing don't mix?
 
There are no professional papers I have ever come across that say synthetic oils actually lubricate better in moderate temperature environments. Very cold - yes. Very hot - yes. But, OTR trucks regularly run 1,000,000 miles on conventional oil regimens.

Synthetics were developed for other reasons than pure lubricating ability ...
 
Originally Posted By: BrocLuno
There are no professional papers I have ever come across that say synthetic oils actually lubricate better in moderate temperature environments. Very cold - yes. Very hot - yes. But, OTR trucks regularly run 1,000,000 miles on conventional oil regimens.

Synthetics were developed for other reasons than pure lubricating ability ...
Oil keeps the parts separated. Syn of conventional what ever else, why would the kind of base oil matter if the parts are separated. Yes we can add cold ,Hot Longer possible life etc but that is another discussion. Marketing works and it works well.
 
That paper addresses lower pour points, better oxidation stability, less fire potential, and a whole slew of factors including reduced heat build-up and vibration for worm gear drives, etc.

But nowhere in that paper does it indicate better actual lubricating properties. It makes no claims that within normal use and normal oil change intervals, that any of a whole host of PAO types actually lubricate better ...

There is no such proof that I can find in that paper or any other ... Unless you are talking elevated operating temps, or lower starting temps, etc.

Having driven big rigs over the Sierras and the Rocky's with EGT's of just shy of 1,200*F for extended periods of time running on good old HDEO or even SAE30 HD, I can say that what counts is engine heat management including oil cooling. These are trucks that averaged 50,000 miles a year and got the oil changed spring and fall at 25,000 miles. They all got dino oil and many went 1,000,000 miles and were re-sold to work again for someone else. None required synthetics.

If I was doing Ice Road trucking, yeah sure. Or only hauling from Mojave to say West Texas, I might consider a synthetic. But these companies were/are notoriously thrifty. If a synthetic could be proven to actually save money over the life of the truck, they'd be all over it - but they aren't ...

The vast majority of lubricating fluids for commercial vehicles is highly refined dino oils, which is some case in the USA pass for synthetics ... But they are not Group IV or V.
 
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I agree with you BrocLuno, about the general lack of better lubrication ability (I’m assuming we are talking about wear). That’s not what synthetics are for, in most cases. Base oils largely just provide the viscosity and cooling, while the additives are what reduce wear dramatically when the lubrication regime is not hydrodynamic. Group III is very similar to PAO. Group II is sigificantly different in terms of volatility, viscosity index, CCS viscosity, MRV viscosity, and polarity. Group V is quite different in characteristics from all other Groups, and most oils use either none of it or very little. Group V is so expensive that oils with significant amounts of it are unlikely to be able to provide cost benefits. The major motor oil companies typically don’t use significant amounts of it because of cost reasons.
 
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