Synthetic or not to Synthetic

I have had a remanufactured motor installed in my 2004 Tahoe. (Kept my old motor for project). Anyway the shop gave me a directions sheet and it states to change oil at 500 miles but NOT to use synthetic oil. Then go 3000 miles and then I can use synthetic if I prefer.

I have not called the shop yet but curious if anyone understands the reason for this guidance ?

That is what the shop says to do . They are the ones who will handle what warranty problems you might have . What more reason do you need ? And yes you should let the shop explain it for you.

There are very good mechanics that post here but if I gave you conflicting advice how would you even know if I knew what I was talking about.

Edit - don’t know what the warranty is on this engine but if the shop does oil and filter changes I would have them do the changes during the warranty period .


Synthetic oils lubricate more efficiently. He wants you to use regular oil to help the rings seal to the cylinder walls. It is a break in procedure.


That is the reason right there…

Thanks tcmichnorth and mustangman for the info. This is exactly what I was curious about.

Volvo-V70 really? Cmon really? If you don’t know just pass. I don’t need to hear something I already know. “cause that is what the shop said to do” ?

Auto manufacturers must do a different process because new vehicles will be delivered with synthetic oil…normal oil that vehicle is suppose to use as outlined in owners manual. I haven’t seen a new engine with break-in oil for any special oil for the break-in period for decades.

With later model cars the machining tolerances have greatly improved making a wear in break in unnecessary.

This 2004 Tahoe should fall well in what’s considered a late model. All I can assume is the builder can’t build to the same tolerances the manufacturer can.

I think this is the correct reason. There may be a bit of… “This what we have always recommended” as well.

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This makes sense…or the manufacturer is somehow doing a break-in before they are shipped. I’m sure a good builder knows what they’re doing…I’m just curious why.

I think most/all rebuilders are using very different equipment to grind, hone, and set clearances than the manufacturers, so I’m not surprised that the break in instructions are different.

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