Air bubbles (foam) on dipstick??

[ericbirk]

Take some oil, throw it in a bowl, spin it with a blender, see what happens.
Before I decided to further my education and get a decent paying job I changed oil at a local lube shop. Bubbles on dipsticks arent overly un-common. I wouldnt be loosing sleep over it.

As far as your "Apparently they even can be caused when oil passes around a sharp angle inside a galley or port" look up cavitation.

On another note, why did you feel the need to add an additive to a fully synthetic oil?

 

[Kernal]

Bringing this back for an update: changed out the old oil, refilled with ~ 6 1/2 quarts Mobil 1 TD Truck and ~1 1/2 quarts Mobil 1 0W-30. I have at least as many small bubbles if not more than with the previous oil (same batch of Mobil 1), I had assumed the additive might have been the cause but maybe not. It seems like it boils down to either a characteristic of the oil I'm using or my engine oiling system is sucking air somewhere??.

 

[Stevesnj]

Could be crankcase venting issue, not venting correctly and building up pressure or something. I assume you are using Diesel oil because you have a diesel engine?

 

[Kernal]

Gas (petrol) 1FZFE (don't want to turn this into a which oil is better thread). Focusing on causes of foaming or air that comes out of solution. Some references mentioned that there is a normal amount of air in engine oils and that the anti-foaming agents usually keep the foaming/bubbles down. I can watch the very tiny micro-bubbles disappear on the dipstick after running the engine up to 2000 rpms, shutting down, checking the dipstick. This is new, never saw that before about 6,000 miles ago, have been using Mobil 1 TDT for about 15,000 miles. The oil pump cover O-ring was replaced almost two years ago and there are no leaks. The main oil pan and pick-up (sump) tube were also replaced three years ago, so one concern is if the oil pick-up tube has come loose.

 

[86tuning]

Any reason why you didn't use 2 gal of the same oil and decided to blend oils instead?

 

[Kernal]

I've been mixing different Mobil 1 oils for years, if the bulk of the oil still has life left on it and the weather has turned cold I may add i.e. a quart of a lighter weight (when topping up), if approaching summer I may add a quart of a heavier weight (when topping up), never had a problem with air bubbles. Talked to Mobil 1 tech support; they said all their oils are compatible with each other and would not cause foaming, although I do wonder if there is something about the 5W-40 Turbo Diesel Truck making it more susceptible to foaming. IDK. I had bought a few jugs of it when it went on sale about a year ago so wanted to use it up, but when I change my oil next I'll probably go with straight 0W-40 Mobil 1.

Wondering if air could be getting sucked in somewhere in the oiling system:

 

[ericbirk]

I mentioned earlier that I used to do oil changes on hot engines for a living. Saw lots its bubbles.
If your dipstick tube is leaking usually the oil will be coming out, not in.

I think this whole conversion is fairly entertaining, you blend oil like a mad scientist. You must be an engineer?