Some 02 and 03 VQ35s have pretty significant oil burning issues, it's well documented. An easy, basic level check as to whether an engine is an oil burner or not is to check the exhaust ports. Some 02-03 VQ35s do not have oil burning problems. Mine does not.
If this is a front engine you're talking about, it is DEFINTELY not worth buying a bad engine in need of rebuilding for $500, as you can find a perfect working order FWD VQ35 for $500, one needing no rebuild. I am not sure on RWD VQ prices as I have never priced one. check
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