Engine oil frothing

[aldogg7]

This past winter I noticed engine oil frothing on the dipstick, and before jumping to the worst possible scenarios, I simply thought it was due to the cold Eastern WA temperatures and short drives (<2 miles) to work with a daycare stop every morning and evening. Once I started doing these daily drives in 2nd gear and letting the engine warm up more, the froth went away, so I'm hoping it's nothing more serious.

Anyway, I'm about to change the engine oil, and I'm wondering if switching viscosity types will help in the winter months. I change the oil once a year, which is about 5000 miles. I've been using 10W-40 full synthetic, but perhaps going to a 5W will help with the frothing. Has anyone had experience with this before? Thanks!

[J!m]

My experience with "frothy" oil is due to water being in it.

That can come from the cooling system, which is where it usually comes from, but it can also come from condensation in the block.

Was it just one oil change that did this, or did it start, and continue to do this?

I assume you have been watching your coolant level closely? The heat is still working fine?

How much oil are you using (burning+leaking) in the 5000 mile run? I would expect close to two quarts added in 5000 miles...

Full synthetics tend to flow more easily at low temperatures (in the same advertised weight) but what specific oil are you using? 10-40 seems fine to me. I think the manual suggests 5-30 dino oil for cooler climates. I don't remember what I was running... I think it was 10-40 dino in my old 1.9 but that was ten years and 70,000 miles ago! Now I run Mobil-1 15-50 synthetic in my S52. The few times I have started it in the cold it was fine (I usually don't drive it in the winter)

[aldogg7]

Thanks for the advice J!m!

This winter was the first time that I've noticed this, but this winter was colder than the last 2 I lived here. I haven't changed the oil since I noticed the froth, but it went away after changing my driving habits and letting the engine warm up more.

I have been checking the coolant levels, and they have been looking good. The heat works fine as long as the engine is at full operating temp, which doesn't usually happen during my short drives in the winter. I'm about to flush the coolant too - is there anything I should keep an eye out for when I do that?

As far as oil consumption, over the course of 5000 miles, I go through maybe one quart, if that. I usually add extra oil within 500 miles of the change.

The manual doesn't give an exact engine oil specification. It just has the diagram of the types based on temperature.

[J!m]

Yeah, the weight per temperature is the key factor. Not too light or too heavy. Dino or synthetic is your choice.

On the cooling system, I'd replace the thermostat and its housing with a metal one. Hoses of course and possibly a Stewart high volume water pump. I didn't see what year yours is but BMW had some water pump issues during E36 production. I think it's cheap insurance.

[Vince70]

It happens to my Ti every autumn and winter as I just drive mine a couple of miles to work and back and it's only condensation.

It's no problem and I've tried different oils etc but it's worth throwing on a new CCV valve for good measure or clean your old one out with a bit of carb cleaner to help the engine breath.