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Deep pan oil volume

ray wilson
Trusted Member

78 R100. I have a deep pan on it, thinking more oil will run cooler and cleaner because the volume dilutes the harmful byproducts in the oil. I use the stock dip stick but have proper deeper oil pump intake. So filling to the normal mark on the dip stick will have the correct level in the crankcase, right? There's so many opinions out there, like the infamous tire thread. 

Topic starter Posted : 01/12/2022 09:24
James Strickland
Reputable Member

There are some owners who would suggest that the best and proper application of a deep oil pan is to increase the volume of air in the motor sump. The benefit there would be to minimize churning of the oil into a frothy foam.  To achieve this goal, an owner would put the specified amount of oil (2 liters?) in the motor and make a new mark on the dipstick.  Try to visualize 2 pistons travelling down the bore to create pressure in the crank case. A greater volume of air under the pistons might reduce the churn.

In a related commentary, My R75/5 churns out a 2 liter refill until it finds its happy place. That happy place is somewhere around half way between  the high/low lines. My 750 had a deep sump on it when I became the owner. I would fill it to the full mark and it would shed oil to about half way. It now has a stock oil pan and it does the same. I observe no real difference on my bike, except the price of an extra quart of oil. Over the years I poured a lot of oil in the motor trying to keep the level at the full mark. It always found its working level. I finally gave up on that, and that was when I discovered that half way on the stick is where it wants to be.

I'm guessing this isn't very helpful.

Posted : 01/12/2022 12:18
Bob Whigham
Estimable Member

My experience with oil levels also, James. Once at the half way mark, the oil level stays the same until next oil change except when I had a bad oil leak. 

Posted : 01/12/2022 14:13
ray wilson
Trusted Member

The way i saw it was back in the day, my dad had mounted a large extra oil filter in the engine compartment (like 2qts) on his 63 352 Galaxy. Sales rep and put 50k a year on it and the extra oil was good for the engine.This is a different situation, so maybe i should put the regular pan back on. No advantages and more oil...


Topic starter Posted : 01/12/2022 14:42
Richard Whatley
Member Moderator
Posted by: @15295

So filling to the normal mark on the dip stick will have the correct level in the crankcase, right? There's so many opinions out there, like the infamous tire thread. 

I installed the "deep oil pan" from Mac Accessories on 3 Airheads so far. The last 2 it was so that I could remove the R100 oil coolers. My riding took me to the cooler, wetter parts of western NC, so hot oil was never a problem. But working around the cooler was a big issue for me when doing general maintenance. So I simply reverted to the pre-oil cooler setup, using the extra quart in the deep pan to make up for any difference.

Like you, I simply used the stock dip stick with the oil up to the OEM oil levels. Never a problem !

In fact, what I noticed was that I never lost that 1/4 quart that was supposed to be lost to "foaming" on longer rides. I don't ride Interstates, so I can't speak to that type riding. But (basically) the further I rode in a day, the less oil my engine seemed to consume. So IMHO, the oil loss and foaming thing is a slow speed feature.


- The Mac oil pan is no longer sold, but I have a spare if anybody wants one.

- I find that the stock R100 pan makes an inexpensive "deep pan" for the R50, R60 and R75 with the flat pan.

[color=blue]Don't hide 'em, Ride 'em !!

Posted : 01/12/2022 15:04


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