Sounds like you
might be confusing two different things here... "Service Engine Soon" light and "Change Oil" light.
"Change Oil" light comes on after certain amount of miles after it has been reset last time. Don't remember whay the mileage is, though...
SES will come on only if the computer detects that some of the parameters do not match the factory specs. It can come on for a while and then be off for a while and come back again etc. There is no "timer" in the SES light.
Best way to find out what the problem is is to read the codes off the computer. At least here in TX AutoZone reads thm for free, I think. If you take it to a dealer, they will usually charge you one hour of labor.
Hope this helps.
TS
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99 Firebird FOR SALE!!!
96 Suburban 4x4
95GRNZ
[This message has been edited by 95GRNZ (edited July 23, 2002).]