Deeper Oil Pan Dipstick Question

[kantuckid]

Here's a "dipstick question", & no , if you answer you are being nice, not a human dipstick. I bought a deeper pan from a 1976 R(is the 722 part number as a 723 & with extension) to go on my 1973 R75/5 project. After reading all the pan info Anton so nicely put together, I still have this question: Do I want to read my old dipstick at a new point, or weld on a 10mm piece & after adding oil as specified for a 1976 ? Obviously I'd rather not have to buy or weld anything to complete the addition of the slightly deeper pan.

[20774]

It's kind of what you decide to do filling with oil. If you want to run more oil without changing the pickup screen, then you should use the old dipstick, filling to the "full" mark. If you just want to run the same oil amount, ~2 quarts, with the pickup extension, then you'll need a new dipstick or an extension to the old one (fleabay or the used parts places probably have one ready to use).

There are pros and cons for either. Best of both worlds would be something in between...you could probably still get by with the old dipstick (plus lowered pickup) and then figure out where to monitor the oil. Provided that the oil even shows up on the old dipstick.

[lmo1131]

I thought the idea behind the deeper pan was to provide more cooling area, and more cooled oil... no?

[doktortim]

A major benefit of more air volume is reduced windage and crankcase pressures and venting. The R100 engines make good use of this idea.

The benefit of more oil is more detergents means a few more miles before next oil change. And a few more miles of safety factor before you run too low.

With the 81+ pan and pickup on my 79, I use the half way point between the lines on my original dip stick as my Max fill. I top up at the low line.

So I run about 200cc more oil, and boost the air volume a bit as well as never blowing the top 1/2 qt out the vent in the first days run.

Anton lines out very well the options for pans and sticks. Note a /5 center stand limits you but /6 and /7 stands are direct swap for the later larger pans.

[8ninety8]

Before pan, whatever type, with pickup extension bolted up, insert old dipstick, take a look-see where the stick and marks are relative to pickup/bottom of pan used. Make mental note to self when checking at two quarts and so forth. Could even make a new mark on old stick to remember. Just trying to process.

[osbornk]

I think you would want to use the same dipstick because you would want the oil at the same level in the engine. I don't think the engine cares how much oil is in the pan as long as it is at the same distance from the engine parts as they move.

[20774]

I think you would want to use the same dipstick because you would want the oil at the same level in the engine. I don't think the engine cares how much oil is in the pan as long as it is at the same distance from the engine parts as they move.

Anton pretty much sums up the advantages to lower the level of the oil in the sump (from his website):

"Additionally, the greater air volume in the sump means less fluctuation in crankcase pressure and therefore less oil lost through the breather."

[kantuckid]

Are "we" saying that the new pan & longer pickup from a /6 (what I have as stated above) needs to be installed ,then ad the amount of oil as is spec for a R75/5 original pan & take note of the new level taken on the original dip stick by that same amount of oil?
Are there two schools of thought/advantage going on here, one being the air space created, the other being the added oil capacity? I've read some of this previously but never decided if which advantage takes precedent. Is there enough "new space" created with the pan I'm using to gain both of these or does it take the even deeper pans to get?

[Walking Eagle]

As often happens, another crazy Airhead person asks the SAME question that I have, and that has happened here, so THANKS to kKid.

My current project is a '78 RS Motorsport, and I just swapped-out the stock shallow pan in favor of a "995" later-model OEM pan, (which is Teutonically stamped "994.") Also (of course) installed the deeper pick-up. I'm installing an oil cooler today, and for those doing this job, my "stubby" center pipe came right out with minimal effort by using a big-assed screw-driver, which fits the slots in the center pipe just right.

SNOWBUM (maybe Anton?) lists the volumes of oil, as follows:

UP TO 1980 w/o Cooler -- 2.25 Liters
WITH Cooler -- 2.50 Liters

FROM 1981 (995 pan) w/o Cooler -- 2.50 Liters
WITH Cooler -- 2.75 Liters

Note that some oils are now packed in LITER bottles vice QUART -- always look, and you may be surprised. . .you may also be draining some oil!

My "plan" is to carefully measure the right amount of oil the first time, and see where it hits on the stock ("shallow pan") stick. Yes, I'll use ALL the "cooler-filling tricks" and so on, and will take the level up incrementally. If it doesn't register, I'll just use a rubber band and attach a length of popsickle stick to the old . . . naaaah, just kidding. . .

I'm certain that if any of this is wrong, one of you wiseacres will tell me. I'm NO kind of expert.

Quite an addiction we have going, eh?

Walking Eagle

[20774]

IMO, the Airhead engine is fine with the amount of oil specified for adequate protection and cooling. Under unusual circumstances, extra oil might be beneficial in terms of cooling...BMW used coolers on some bikes but not all. I think adding the air volume but keeping the old amount of oil might have the most benefits. Adding oil does increase the "chance" for cooling in terms of added surface area (along the sides of the pan due to the increased height...what is that, like maybe another 1/4 to 1/2 inch? Not much I think.) and the fact that the oil tends to "dwell" in the sump a tad longer due to more volume to circulate.

Maintaining the oil's lubricating properties as well as the additive package is what it is all about. That can be done in a variety of ways, including changing oil more frequently as well as keeping the temperature within operating limits. Doing what the specs call for in terms of change intervals and original volume will provide for a long life to the engine. These other changes can mitigate damage to a small degree and might extend the life of the engine...but probably not in terms that we could really measure.

In the aircraft structural integrity world, we're always chasing the most anticipated failure location. We figure out ways to fix or monitor that location. Once "fixed", the next most threatening failure location pops up...and our focus shifts. And so on...

My 0.02...

[R100RT_Mark]

First, and somewhat regardless of oil fill level, I think that it is vitally important to match the “Oil Pump Strainer” (BMW-speak for the “pickup”) and Oil Pan as I believe that with a mismatched deeper pan and a high effective pickup point there is an increased risk of oil sloshing around and a too-high pickup sucking air. A new Oil Pump Strainer is $10. No need to skimp.

There as some other nuances. For example, my 1993 R100R, which as stock has the same engine as R100GS from the period and, hence, a shallow oil pan, has a “Covering Plate” baffle as part of the Oil Pump Strainer. My 1994 R100RT, which as stock has a deeper Oil Pan, does not have the Covering Plate.

For me, for anything not used solely for track days/competition, the added air volume in the sump is the prime benefit of a deeper Oil Pan.

The obvious BMW stock “best” set up is to use matched (a) deeper Oil Pan, (b) taller Oil Pump Strainer, and (c) longer Dip Stick (new about $25), with the fill level determined by the latter’s markings. Simple. No guess work. No second guessing.

[PGlaves]

To me modifications need a motive. That is there ought to be a goal in mind. So for a deep oil pan the motivation might be cooler oil. Airheads are somewhat prone to cooking the oil. Larger volume can help this. Or the motivation might be to extend the life of the additive package both for detergents and viscosity stabilizers. These motivations might argue to keep the "level" the same and the volume greater.

Or maybe reduced oil consumption and reduced blowby are the goal. Those grimy carb air tubes soaked in oil from the crankcase vent can be irritating. With this goal then maintaining the volume at a lower level (with lowered pickup of course) might be what to do.

Or maybe having a cool bike with another aftermarket accessory is the goal. Unless I know why the rider wants the deep oil pan in the first place I can't know how to balance the tradeoffs.

[20774]

Airheads are somewhat prone to cooking the oil.

Paul -

Can't say that I've heard this as a major problem before. In my limited experience, I'd say they are not really that prone to overheating. It sounds like you've seen quite a bit of this...any more background?

[PGlaves]

Paul -

Can't say that I've heard this as a major problem before. In my limited experience, I'd say they are not really that prone to overheating. It sounds like you've seen quite a bit of this...any more background?

I wouldn't say it is a "major problem" for riders who are aware of the limitations but it will certainly bite those who aren't. Generically, Airheads are purely air cooled, and depend on air flow past the heads and cylinders to cool them. Thus fans are used if a motor is stationary, running, during a tune-up for example. If not they get hot very quickly. Nobody ever told me I needed to blow a fan on my lawn mower if it was stationary.** But they do for Airheads, with good reason.

Oil is heated differently at different parts of the engines too. Oil passing the vicinity of the exhaust valves gets very hot. Idling at stop lights usually isn't a problem, but a long cycle time light with a 4 minute wait can overheat the engine where you live. Traffic jams, highway accident traffic snarls, long suburban stop-n-go, all can easily raise the oil temperature in an Airhead to over 300 degrees.

Thus the oil gets cooked. Ash deposits form. Components get gummy. Viscosity can plummet, etc.

** - back when I had a lawn with green stuff that needed mowing, that is.

[lkchris]

When putting the 1981-on larger oil pan on an earlier engine, an extension of the oil pump pickup is required. (It's a spacer block) So is a different dipstick. Have done this mod to my 1984 G/S which came from factory with old-style shallow pan drilled for bash guard. I've obviously given up some ground clearance and ability to mount the BMW bash guard, but that's meaningless to me.

So, if there's indeed a difference in capacity between some early 1970s engines, why not just go to realoem to check whether dipsticks--and oil pickups--are different?

For my G/S, it was obvious what to do just comparing G/S parts with R80ST parts--the latter fitted with the new deep pan from the factory.