OT..coolant and oil

I have a 1987 Caprice 4.3L V6 with 200,000 miles that I bought new. It runs smooth, does not smoke or burn oil and on a trip I can drive 8hrs 20min before refueling. I have an 04 and 06 but I’m keeping the 87 as a runaround for me and my dog.

Yesterday I was siphoning out green coolant to install a new thermostat and noticed the coolant was darker than it should be. And there was some unfamiliar white sludge and flakes on the thermostat. (Note. The dipstick shows no indication of coolant in the crankcase) When I looked into the coolant reservoir it was almost pure engine oil. So I removed and cleaned the reservoir then renewed the coolant.

I can’t see how straight oil got into the coolant reservoir except for it being put there. The place where I have my oil changed tops off everything from a bank of bulk hoses. The only thing I can figure is that one of the kids meant to grab a coolant hose and got an oil hose by mistake and failed to tell me.

Question: Would putting a quart of engine oil into the coolant reservoir,
A. Decrease effect of coolant/anti-freeze
B. Harm the engine.
C. Lubricate the oil pump.
D. Have no affect at all.

Dell

The oil won"t directly harm the engine but it can coat the passages in both the block and the radiator, reducing heat transfer and causing overheating. It might also eventually soften the rubber parts of the cooling system.

You should clean the system out, but the best way to do that will depend on the details of the design. I used lye when I had oil in the cooling system of my 8N, but that"s all iron, copper, and rubber.

You should make the oil change doofuses pay for it. And change your oil yourself in the future.

I agree with john.The oil in the reservoir will not hurt your engine besides cloggin up your heater core and or your radiator. I think I would flush your system out or better yet let the ol boys that made the mistake do it. I use Cascade dish soap when I flush out the engines at work with this when I get an oil cooler bleeding over to get the oil out. An ol hillbilly I learned alot from used it.

Wonder what would happen if I put a half cup of Cascade in the system and ran it for a week then flush. Would it bubble up like "old faithful". Temps are going to be in the mid 40s this week.

One suggestion...if your car has an end-tank transmission cooler, this could be injecting (leaking) into the radiator. Could be ATF instead of engine oil.

I am more likley to believe the yooho's accidently injected motor oil into the coolent reservoir if you got the car serviced recently. I do not think 1 qt of oil will ruin a system holding 10-12 qts... I also agree with the auto trans cooler idea. Check the auto oil for coolant.

Regardless, flush the system somehow. I own 2 Cheverolets and 1 BMW/Mini Cooper. I have owned only Chevrolets until we bought the Mini. Through all the years I have NEVER heard of oil in the coolent reservoir without coolant in the oil. I also have never heard of an auto trans cooler rupturing either.

[b:5193913c75]Sorry, had to post the 0-60 in 5.9, 140 mph top end, 38 mpg... :twisted: [/b:5193913c75]




Charles

I let the machines sit here and run for a long time with cascade in them,It really doesnt bubble up just kinda looks milky(after the oil is out.)I let them run and get hot so the thermostat opens then drain it...I keep repeating this until its all washed out.