Originally Posted By: Viggen
Originally Posted By: fdcg27
This is very possible.
The fresh oil comes with fresh friction modifiers, so it is possible that mileage really does improve after an oil change.
No placebo effect involved.
So do all current oils dino and synthetic come with these modifiers and generally how long (in miles) do they last?
I've never been a big believer in statements like the OP made but maybe if what you say is true it is possible.
I personally can say that following a OC (about every 6k mi) in my 15 year old VW Golf 2L that the engine definitely seems to operate more smoothly and quietly.
Using the search function, I found a number of threads in the Interesting Articles forum.
It appears that FMs are required to make the really light oils suitable for use.
I would therefore expect that any 20 grade would have a healthy dose of FMs, and any starburst oil would as well.
I didn't look far enough to tell you how long these additives last.
I myself have seen improvements in fuel economy with certain oils.
For example, the BMW has been about 8% more economical on M1 15W-50 than it was over the same period in the same type of driving than it was last year on Tection Extra 15W-40.
The Castrol product is a HDEO, a fleet oil aimed primarily at diesels, so I would expect it to have little or no FMs.
The M1 is clearly a PCMO, although many bike owners favor it.
The concern of many riders is that a high FM level wil lead to degraded wet clutch performance, so I'm not sure what level of FMs this oil has.
It may be that the oil simply uses a proportion of ester basestocks, which also deliver lower friction.
In any event, something is happening with this oil that cannot be explained by the grade and high HTHS.
I wish that XOM were more forthcoming about the composition of the variuos grades and flavors of M1.
That way, those with some knowledge could make a more informed choice, and those who know only the brand would remain ignorant, since they would neither know nor understand the significance of the information.