When checking the oil tonight I notice a lot of rust on the dip stick that hasn't been there in the past. There is now white/tan foam/bubbly (with water inside the bubbles) in the oil fill cab and down the tub.

98 z28 SS LSI no major mods, but it does have 194K+mi. I haven't had the car that long, only 7-8 months. Regular oil changes every 3000mi with high mileage blend. I haven't noticed anything out of the ordinary and I check the oil once a week due to a small leak. The oil always looks the same as the day it was pourd in, nice clear gold color. The weather has been pretty consistant, COLD, below or at freezing for the past month or more. Is this a common issue on the LSI or something I need to take to my mechanic for a possible rebuild. Engine is strong and seems to have good compression. It is an automatic so if it would be best to get rid of it say so, I would rather have a 6sp. I had a 92 with the 305 and it never had this issue.

 

has the car been driven a bunch of short distances lately?

Ive seen some cruddy oily/water buildup in the oil fill cap area before. MOST likely, you haven't been driving it far/long enough to fully evaporate the moisture out of the motor and oil. OR its hitting the temps just right that when it cools, moisture condensates in the dipstick tube and around the filler cap.

If your worried, change the oil now; and get a really good look at it and see if the stuff that comes out of the pan has water (coolant) in it. and just monitor it from there.

Chances are, its fine. Especially if its not using any coolant.

 

Daily driver averaging 35 miles to and from work in medium to heavy traffic on the highway. 50/50 stop and go with interstate travel. The only issue with the engine is low oil pressure after a long run and the engine acts like its going to stall. Does this once or twice then perks back up to a mustang killer.

 

Check for coolant consumption.

That's indicative of a head gasket failure.