Recently had oil change on fully rebuilt 350 Buick by an engine builder (less than 1500 miles on engine, and we did a break-in oil change at 500 miles) no major performance build-ups besides, Bullet cam, Cloyes Timing Chain, ported/polished heads, TA Performance Aluminum intake. When the oil was removed it looked like Chocolate Milk (a darker version than what you make at home or buy at grocery store) With that said we sent the used oil out to be tested for foreign bodies inside the oil. It came back with about a 10% read on Ethylene Glycol in the used oil. I’ve asked numerous experts, some say blown head gasket, cracked block, cracked heads, cracked intake, and the list of guesses go on. I did get a consensus on that it probably is not a cracked block, or blown head gasket. No performance issues with vehicle at all, no smoke blowing out at all. We are taking the approach that the intake manifold gasket has a breach. We are replacing it, then doing a compression test on all cylinders to see if we have a culprit. Using Valvoline w.Zinc for Oil...btw. Any comments or feedback would be appreciated. Thanks!
I would also go with the intake gasket first since there’s no performance issues. Just be real careful pulling the intake and you may be able to see where it’s leaking
Yes gasket sealer was used. One of the areas where coolant flows through looked to have a lesser amount of gasket sealer than the other ones. Everything has been replaced. Going to change oil, add dye to coolant then fire her up to see where we are at. Thanks to both of you for your feedback...much appreciated. Chris
I use the Evans waterless coolant and when that gets in the oil it makes a big mess. Cannot simply flush it out like the issue you have. This stuff turns to a jelly. One reason my engine is currently on the stand in the process of a rebuild. You can bet Im gonna pressure test the coolant system before it goes into the car.
Used the metal valley gasket. Guys, thanks for the feedback. Will definitely take into consideration. Cross fingers!
This is a dumb question, but was the oil drained into a clean container? No chance of contamination I’m saying / asking....
10% would be 1/2 a qt of coolant. And the "Chocolate milkshake" is a classic and dead giveaway of a good amount of intrusion into the crankcase.
Sorry for so late in replying to everyone. Replaced intake manifold gasket with plenty of sealant this time. Ran and changed oil twice. No trace of ethylene glycol in oil. Car runs and performs as it should. I will continue to monitor the situation.