fly1977

I know there are other threads about over fill of oil in Z51 cars.I just had oil changed at local dealer (not dealer I purchased from) After adding Dextros with me requesting Mobile 1 they changed oil again with Mobile 1. Thinking they knew what they were doing I did not check behind them. I noticed car seemed just a little sluggish. I checked Oil after letting set for 7 minutes and oil was almost to the top of stick. Put car on my lift, drained out 1 quart and oil level is still a little above upper hash marks. Car seems to be normal now but I am concerned about what damage has been done to engine running at high oil level for about 200 miles. From now on I will change my own oil and forget about the 5 free oil changes. so what damage can I expect from overfill other than oil in intake ducts which I have not inspected yet. Thanks Guys and sorry for the long thread.

Bill Dearborn

More than likely nothing. The engine can easily handle a quart over since it is recommended that owners install an extra quart when tracking the car. Sounds like the oil change guy was reading the wrong section of the manual.


Bill

fly1977

Bill, I don't think the Tech was reading anything. He probally makes minimum wage. So easy to screw up a $75,000 car. I will do all oil changes myself in the future. GM can keep the 5 free oil changes if they do not have a qualified tech to do so, and at this dealereship I am sure they do not!

RickMN

Overfill can increase the chance of oil getting into the intake area. It can mess up the readings of the MAS (giving false readings of airflow) and also make a mess of the air filter (partially obstructing airflow). In extreme cases, a check engine code can be triggered due to the computer attempting to overcorrect the fuel/air mixture based on the false MAS readings.

Mariano

Unless you tracked your car during that 200 miles, I highly doubt you incurred any damage. The concern, if any, is oil ingestion. To ease your fears, check your air filter box for the presence of oil and clean it if needed.
Mariano (Alfie)

FKING1

Not necessary to add extra oil when tracking a dry sump car, that's why it is dry sump!
It is common to add extra in regular oil pan sump cars when tracking as I do on my
autocross car.

fly1977

Thanks guys for the info. I did pull hose off of the air intake today and looked inside. did not notice any oil and car seems to run fine. Service managers and their techs need to be more educated.! In the future I will change oil my self

Jims66

I'd go and explain what happened and why you're choosing to do all your own oil changes from now on....... AND then ask them for enough Mobil1 and 4 oil filters for the remaining "4 free oil changes"... Then let them know not to worry because you'll eat the labor cost if they throw in a set of free floor mats !! I'm just say,n.

Magister Ludi

RussM05

Mine was overfilled and there was oil in the intake tube when I swapped it out for the Halltech system.

I also noticed the outer exhaust pipe on the muffler had alot of black soot. When I changed the oil and made sure it was at the right level, the soot problem disappeared.

bob guzzy

Mine was overfilled from day one, I kept checking for oil in the air filter system but never saw anything in it.

I took it apart to check inside, I twisted and turned it in all positions not a drop of oil came out, I washed it out to be 100% sure.

At 1500 miles I changed the oil I do believe I added 8.5 or 9 quarts, I added oil in small amounts until the oil stick read in the middle of the hash marks.

I made sure the engine was at operating temperature then let the car stand for 15 min to check the oil level.

I'm not really hard on a car I do get on it now and then but they are just short bursts in 1 and 2nd gear.

Gr8ful

Fly1977, I am with you. I changed my oil at 1k and installed two magnetic drain plugs. I never had a good service experience at the dealer with my C5 so I'm not going to even chance it with the C7. Also I really like looking at the C7 including the underneath.
It's only about $50 it do it myself and I know it is done right.
My $.02 worth.