My Engine Was Using Synthetic Motor Oil – Now Petroleum Based

Reader Question Austin,

My question is, I am buying a used 500 CC 4 wheeler, it came with synthetic engine oil. I requested that the vehicle be serviced before it was delivered to me, and the dealer put in regular 10-40 motor oil as well as a new oil filter.

I am not sure that this is acceptable, what do you think ? The vehicle is a 2004 Bombardier “Quest” approx 1500 miles and 70 hours on the machine. I realize that regular petroleum oil is cheaper than synthetic but my concern is the engine.

I would appreciate your thoughts on this, Thank You, Thomas

Hi Thomas

You are ok, but as a rule of thumb is it best to choose an oil and stick with it for the life of the engine, but since things are so new, I really don’t think any harm was done. I would ask the dealer if they use regular oil instead of synthetic as their rule of thumb.

I personally do NOT use synthetic in my shop or in my personal cars, I just can’t see the benefits outweighing the additional costs of the oil. There are MANY people who will disagree with me on that…so I would say personal preference and emotion play a larger factor in the type of oil used more than facts.

Follow up


Thank you for your opinion on motor oil’s, you’ve echoed my thoughts. I have been a mechanic for over 50 years, I realized I was not as knowledgeable on the pluses & minuses of synthetic oil as I should be. I was a jet engine mechanic. In the A.F & Navy for 20 years and synthetic oil is ALL that is used in these engines, that is because of the high temperatures that they operate at.

My new “Toy” is liquid cooled and will be operating at a LOT cooler temps than the jets I used to work on. I will stick with the petroleum based oils, I was concerned about the switching from one to the other primarily, the “Motor Oil Bible” cleared that up for me.
Thanks again, Tom

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