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Q. Is one synthetic oil better than the other?

Why does Mobil say they can go 15,000 miles, and Amz-Oil to 25,000 to oil change. while others just say change at recommended intervals according to the book? Also how far can I go with syn oil in our truck fleet, and again, is one oil better than the other?

June 9, 2014

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A. Your question regarding the products you have referenced need to be directed to those companies to support their claims. However, there can be a difference in the synthetic composition of engine oils. More importantly, first and foremost, you should check with your engine oil manufacturer for their recommendations and should never accept an oil change recommendation just on the strength of an engine oil claim.

There are several factors that influence or impact engine oil change intervals. In the case of heavy duty diesel engines, up to 40% of premature lubrication engine failures are cooling system related which has little to nothing to do with oil quality, synthetic or no synthetic. Other contaminants such as dirt, fuel and soot should also be considered. Without oil analysis to evaluate oil condition it is somewhat like asking a doctor if you can run a marathon just because you believe yourself to be healthy.

The severity of operating conditions should also be considered such as trailering, loads, high temperatures, stop and go versus over the road or steady state driving. The filter type, fuel consumption rate and oil consumption are also factors that engine manufacturers consider in recommending oil change intervals.


The bottom line is that it is important to take several factors into consideration starting with your engine manufacturer’s recommendation if the plan is to optimize engine life and protect the engine warranty.

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Author Bio

Mark Betner

Lubricants Expert

CITGO Lubricants

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