MAC Deep Oil Pan

Good evening,
I recently bought a 1979 R100RT that came with a MAC Deep oil pan. nice idea, but can someone enlighten me why put this on? I understand the idea of more oil and more cooling, but here in my part of the world heat is really not an issue. My second question in looking at the MAC web site it may not be recommended for a 1992 R100RT, again why not?

Anton has a pretty good page on oil pans, stock and aftermarket:

http://www.largiader.com/tech/oilpan/

Why a deep oil pan? There's a couple of schools of thought that I can think of. One is to run more oil...more oil running in the system stays in the sump a bit longer and cools down a bit more. Another is to run the same amount of oil (ie, 2 liters) thus lowering the height of oil in the sump. This allows more air volume so the pistons aren't fighting the increasing air pressure as they travel to bottom dead center. Plus, lower oil height means a lowered chance of the oil being whipped up by the air rushing around inside the sump and creating a mist which then has to be taken care of by the breather valve. Along with the bigger air volume, there's a smaller increase in internal pressure, thus a bit kinder to the engine seals.

Can't say why it wouldn't be recommended for a late model RT. I can guess maybe centerstand clearance. Maybe the RT has an oil cooler making a need for additional cooling unnecessary.

I don't understand the dislike for the deeper oil pan. The Airheads were known for oil consumption. According to Rusty at Max's, BMW had issued a statement that those airheads would consume approx. 1 qt. of oil per 700 miles !!! I kid you not.

So the deeper oil pan seemed to help me on my '78 R100/7. I replaced the breather valve with the newer style, made sure the drip down hole was cleaned out, and then added the pan. Improvement for me. Less oil consumed, and more oil being allowed to circulate.

I did, at the time, as suggested by Kurt. Instead of adding another full quart of oil that the deeper pan would allow, or keeping the same 2-quart amount as in original (assuming one also dropped down the oil pick-up suction tube and filter), I compromised and went half way. I put in 2-1/2 quarts of oil, thus had more oil to circulate AND about 1/2 quart more airspace to stop the oil foaming and being sucked out by the breather.

I never regretted it.

Both pistons going up and down at the same time can enlarge/reduce the crankcase volume pretty quickly. The deeper oil pan can help reduce the problems with that.

b25bsaboy said:

I recently bought a 1979 R100RT that came with a MAC Deep oil pan. nice idea, but can someone enlighten me why put this on? I understand the idea of more oil and more cooling, but here in my part of the world heat is really not an issue...

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Rick:

You really can't have too much oil for cooling, even living where we do. On a recent, slow, transit through Missoula on a hot day, my 2005 R1200ST got so hot that it started clattering like an airhead before I parked it for the night. And it has a 3.7 litre capacity.

And BMW's engineers increased the oil capacity by half a litre, on the 1980 Airheads.

The only disadvantage of the larger capacity sumps may be centre stand interference, and a slightly slower warm up. Also, IIRC, some of the early airheads didn't have coolers.