First Airhead, Premature Oil Change?

[pstanfo4]

Hi All,

I'm new to the forum, having recently purchased my first BMW, a 1974 R90/6 in decent running condition. Not knowing anything about the maintenance that had been done on the bike I decided to change the fluids after a few short rides, thinking it was a wise decision. After I had done this and gone on a few longer (2+ hour) rides I started to notice that the push rod seals and oil pan gasket were weeping a small amount of oil. I ordered the gaskets and know that I have to completely drain the oil to replace the oil pan gasket. My beginner question is whether or not, given that it's brand new oil, I can drain and then re-use that oil or if I really need to get all new oil. Thanks for your expertise!

 

[20774]

Welcome to the forum! The R90/6 is a good bike to start out on. I understand the decision to make regarding replacing the oil. If it were me, I'd put new oil in...I don't think I could drain the oil sufficiently well to consider it contaminant free for reuse. What type of oil did you put in it? Rumor was in the early days of synthetic oils, they tended to not have the seal-swell additive and bikes that had only seen mineral oil would leak with synthetic. Probably not much of an issue these days. Maybe switching to the oil used by the previous owner...provided it was a decent oil

That said, can you deal with the oil pan leak and extend the time you have on the new oil? Have you gone around to retighten the oil pan bolts? I don't know the torque, but typically I put a 10mm socket on the end of a nut-driver and use a criss cross pattern to snug the bolts up. You might be able to stave off the oil leak and get more riding in.

As for the pushrod tube seals, changing them can get a little involved. Unless they're "pouring" oil, people usually put that off until there is another reason to pull the top end. How many miles on the bike?

 

[ccolwell]

That happened to me on one of my airheads when I used Mobil one, the R90S as I recall. A return to Castrol GTX solved it.

 

[robsryder]

I also had a number of leaks of airheads after use of synthetic oil (Mobil 1 15w-50). I went back to a regular, motorcycle oil. It is suggested to use a motorcycle specific oil that has higher levels (> 1200 ppm) of zinc (usually as a additive known as ZDDP). The softer zinc protects high wear surfaces (e.g. cams and lifter blocks).

On one of my airheads the oil leak stopped soon after replacing the synthetic oil. On another (a R60/6) I ended up replacing all rubber sealing surfaces (gaskets and seals). I found the rubber silicon gaskets for the valve cover and oil pan to be effective in eliminating leaks (follow instructions carefully regarding use of silicone gaskets).

A valuable resource for information for airheads is Snowbum's website. Snowbum no longer maintains this website; hopefully the contents will be archived somewhere. Here are a few links that may be useful -

https://bmwmotorcycletech.info/oilessay.htm

https://bmwmotorcycletech.info/pangasket.htm

https://bmwmotorcycletech.info/

Info on silicone gaskets -
https://www.rockypointcycle.com/c-bmw10_lifetime_silicone_gaskets.html

More airhead tech articles -
https://ibmwr.org/index.php/airhead-tech-articles/

airhead club (good to be a member of!!) -
https://www.airheads.org/

Somewhere there is a big list of resources, but I can never recall where it is...

 

[20774]

A valuable resource for information for airheads is Snowbum's website. Snowbum no longer maintains this website; hopefully the contents will be archived somewhere.

As far as I know, Snowbum is still well involved in his website. The bottom of the Tech List page shows that he last made a change on June 22. He states on the page that the website is now hosted by the Vintage BMWMO club on their servers. He still has full control for changes, etc.

 

[pstanfo4]

Thanks for the great information everyone! I put the Liqui Moly 20w-50 Street oil in it. I also have not actually tightened up the bolts under the oil pan. I'll do that before I go any further.

 

[stevenrankin]

Is it worth it?

Yes, you can drain and reuse the oil you put in. You have to ask yourself if it is worth the messing about draining it into a suitable container? A second question would be just how many miles did you put on it? It would make no sense to drain and reuse oil after I would say 500 miles but that is my estimate.

Personally, I feel oil is cheap enough and I don't like messing about with draining and trying to refill. That is my personal feeling.

As to the leaks, you may get lucky with the oil pan in it may just be loose or a loose bolt. However, there is always the chance the gasket is shot and worse yet is the previous owner overtightened a pan bolt and stripped it or more than one. I don't have the specifications for the oil pan bolts torque, one of the other guys listed references for such things. If I recall, the torque setting for the oil pan bolts is not real high so it is common for people not using a torque wrench to over tighten and strip them.

Push rod seals are a very complicated job to change, There are videos on line from such sources as Brook Reams and others who while not exactly covering their replacement will at least cover how to take the top end and such apart so you can change them. Sadly, Clymer and other books are a bit useless as they try to encompass all models instead of focusing on one. If you are in an area of winter down time, I would leave the push rod seals till then unless they are leaking real bad.

It is possible the previous owner cleaned the bike up real well and hid the fact these things were leaking until you the new owner got it and found them. I won't get into an oil debate, synthetic versus mineral or types of oil. Plain and simple the seals and gasket could be leaking for other reasons than the type of oil you put into the bike.

I will say, use a oil designed for air cooled engines with the proper additives there are a lot of choices. Anyway, good luck, if you are near Rochester, NY, I may be able to help. St.

 

[nickrides]

P4
Reuse that 2.5 qts of oil, think of the money you'll save and you'll fit right in.It's well documented that the cheapest thing on a BMW is the owner, ha ha.
Nick
1978 R-80

 

[robsryder]

As far as I know, Snowbum is still well involved in his website. The bottom of the Tech List page shows that he last made a change on June 22. He states on the page that the website is now hosted by the Vintage BMWMO club on their servers. He still has full control for changes, etc.

This is great news. I thought that Snowbum had sold all his stuff (bikes included) and given up his website. I thought that the ABC was going to try and host it, but I am glad the Vintage guys are doing this.