Originally Posted by Vinman

Ive been using Valvoline high millage synthetic blend oil. I recently switched to Valvoline full synthetic oil. Pretty much right after i did my oil change, my check engine light came on.

I was wondering if the full synthetic could have anything to do with this? I doubt it. Is your oil pressure okay? I use synthetic in several vehicles with over 100,000 miles on them with no issues).

If its too full could it have something to do with it? It is just over the full line on the dip stick. Approximately an 1/8th inch over the full line. My 1996 S10 Blazer (when oil/oil filter is changed and topped of with 4.5 qts of oil) has an oil level on the dipstick 1/2" above the full mark. No issues with the way it runs or with check engine lights due to this.

Lastly, what do you guys think about the synthetic oils? Good? Bad? I only run regular oil in my really old cars. Mostly because all have oil leaks. All the newer vehicles (1995 and newer) get synthetic oil. The engines run "easier" with synthetic vs. standard oil. The 6 cylinder 4WD's all go over hills in overdrive out on the interstate that they drop down to 3rd gear in when I was running standard oils in them). That says to me the synthetic oils reduce friction in the engine.

Originally Posted by Vinman

Hey thanks for the replies. I didn't think the oil should have anything to do with the light being on, but i wasn't for sure.

It was just a coincident that it came on right after i changed the oil. However, i did fill it with gas too right before the light came on. I think i will fill it up with some premium before i go in to get the code checked. I tried going to advanced and using their code reader but it kept telling me to hook it up to the vehicle. So then i went to auto value and tried their code reader it wouldn't come on at all. So i think I'm going to have to spend the big bucks and have someone fix my plug that the code reader plugs into.

Originally Posted by sigforty

Interesting, maybe the connection was loose. I know some of those code readers I actually have to turn the truck on for them to read.

If you just filled up, it maybe the gas cap was not tight enough.

Originally Posted by Vinman

I had thought the gas cap was the prob as well, but i have loosened it and tightened it and tried to reset my computer by unplugging the battery. Unless the gas cap has failed completely... its not the problem. It is insane how much a mechanic will charge to hook a vehicle up to their computer.