Gear box oil foaming - update

From the last post: I was running TSC 85w140 in a new 6 ft tiller and the oil had foamed.

Lots of people said just run it, its fine, others said get a better oil, TSC is cheap oil, some said synthetic.

I pulled all the oil out the gear box with a vacuum pump. Only the top 1/2 inch was foamed/bubbles. The rest of the oil looked fine. The side case, I pulled the drain plug and the oil came out good too. So I didn"t drain all of the side case.

I filled the gear box with new valvoline, and had to top off the side case with 12 oz. of valvoline. I then went out and tilled 3 acres at 540rpm on the PTO. A full 4 hours of running.

The results: Absolutely no foam in the gear box or side case. Both cases looked perfect without foam or little bubbles (air entrenchment).

I guess I am wondering does the valvoline and other better oils contain some sort of anti-foaming agents? The side case had 48oz of TSC oil topped off with 12oz of valvoline. Was the 12oz enough to stop the foam? I can"t think of another way to test it, 4 hours straight. I checked the temp of both boxes with my hand, neither was too hot to hold on to (yup, I shut off the PTO).

Any ideas?
Thanks,
Rick

Is there a breather on the gear box?

Gary

Years back (late 50s) when Case first introduced the first Backhoe/ Loaders they had a problem with the hydraulic oils of that vintage holding air and foaming to the point of losing performance and pushing foam out the breather. At that time Case supplied a small bottle of "defoamant" and just a few drops from a medicine dropper was all that was required to "treat" the system, (guessing 10 gallon reservoir). Contrary to what many believe there is a difference in products and that is reflected in the price you pay. It is certainly possible that the additive package in the Valvoline that you added was enough to stabilize the whole gear/ chaincases. I would do my best to get all the old lube out and replace with the higher quality product. JMO, mEl

I guess I don't understand the original problem.

The oil was foaming. So what? It's just a silly gearbox.

Was it coming out the vent or what?

Allan

foaming is due to the physical and chemical properties of the oil and additives in the oil.

Poorer quality lubes are more likely to foam. Lucas additives often create foam as well (in testing).

AIR (foam) makes a poor lubricant!

used to run many right angle gear box's that require 90w or 85w90. Trying all oils available,the valvoline gear oil ran the coolest .So we used it from then on.

Allan in NE.
The original problem was foam and a lot of air bubbles in the oil (air entrenchment). Looking in from the fill plug, I could not tell how much foam there was. So I was a little worried as others said, air does not make a good lubricant.

Mel.
I agree, you get what you pay for. I never had a problem with the cheap TSC oil up to this point. All my other equipment doesn't get ran under the amount of load that the tiller does for the extended periods of time. Maybe thats when its shows better oils are worth it.

IaGary,
Yes, the gear box and side gear cases have breathers in the fill plugs. Thats how I first started investigating. I had some oil slobber around the vent of the gear box. When I looked in from the top, I could see nothing but large foam bubbles.

It looks like as I service the other gear boxes I'll convert them to a good grade/brand of oil.

Rick