Vintage BMW Motorcycle Owners

It was discussed a lot, I know.
But then again, 40w old-school oil is getting more and more difficult to find these days, at least over here in Israel. So the old bike guys come up every then and now with a new idea. Last I have heard is a 15w/30 oil type, mentioned for Diesel engines. All oils will work ok on spot, but long term influence is what we’re talking here about.

1. What do you think?
2. What are you using if the old version is unavailable? Any modern substitute?

By old school, I'm assuming you mean single weight 40w non-detergent oil. Yes, it's hard to find but I'm sure it's out there via mail order.

I would recommend avoiding anything designed for a diesel engine. The combustion environment for a diesel and gas engine are not the same so the oil will react differently. For the older engines, an API rating (US specs) oil of SG/SH is the best. The big push in the US was to reduce the anti-wear features in the SG/SH oils because of problems with automobile catalytic converters. But oils that are made specifically for motorcycles are exempt from that and can maintain these additives. Modern oils will be detergent oils.

The problem with detergent oils is that they hold combustion products in suspension so that the oil filter can scavenge them out. Ooops...no oil filter on the pre 1970 bikes! Non-detergent oils let the small particles sink to the bottom of the oil pan so they could be cleaned out. If the switch is made to a detergent oil, expect to change the oil much more often before the oil gets too dirty. Typically people will change them once a year or every 1000 miles.

Thank you Kurt for this detailed answer.
I have no problem at all changing the oil more frequently.
Is it just this issue, or is there also a thing regarding modern oil attacking in some way the old-school bearings?

For engine oil, it's not a problem...certainly not for a '52 R51/3. There has been some discussion about gear oils and how high sulfur content GL5 can attack bronze bushings in transmissions and final drives. Beginning in 1970, BMW recommended GL5 gear oils. Before that, and it's somewhat unclear, there might have been an issue. Vech has an article on this:

http://www.benchmarkworks.com/articles/ ... aroil.html

The way I've heard this that it happened in a Volvo car, so the natural "extension" was to BMW motorcycles. I've not heard of BMW motorcycles falling apart on the sides of the road. But I suppose it couldn't hurt.

Vech recommends Valvoline VR 1 high zinc especially for flat tappet engines, in either 30w or 40w. That is what I use exclusively.

Icarus

The Valvoline VR1 is a good oil. It is a detergent oil and comes in grades of 10w30, 10w40, maybe 20w50. I'm not aware they sell non-detergent or straight-weight oil.

I only see multi-weight online. Here's Valvoline's site for 20w50:

https://www.valvoline.com/our-products/ ... racing-oil

And more info:

https://sharena21.springcm.com/Public/D ... 162d889bd3

That said, I did find just 40w online, so I guess it exists. I just didn't know. I've run multi-weight all my life, so I will continue with that rather than switch.

I’m not sure the VR 1 HIGH ZINC comes in a multi weight. I think only 30w and 40w. I may be wrong though. The high zinc is important for flat tappet old school, non cat equipped engines. Vech suggests 40w summer and 30w winter. I know the 40w is pretty stiff when it is cold!

Icarus

I had many bottles of 20w50 oil tested in 2013. On the dino oil side, Valvoline VR1 racing oil was one of them. Their phosphorus levels were 959 parts per million, while zinc was 1135 ppm. What you want is a combined ZDDP number of 2000 or so. Valvoline was 3rd highest behind Spectro 4 at nearly 2500 and BMW's oil (which as the time was repackaged Spectro) at slightly less than 2500. That was just 20w50. I have no information on any other weights of oil.

I chose 20w50 for my testing because I was primarily concerned with my /7 which requires that oil. BMW had changed supplies of their oil so I have now gone to Spectro 4 for my /7.

1969 r60/2 US model

Engine: Valvoline VR-1 Racing oil, 30 weight.

Gearcase: StaLube Gear Oil GL-4 (you know why).

Rear Wheel Drive (Final Drive) SAE 90W

Rear Swing Arm SAE 90W

I use Valvoline 80-90 in both of the above.

Change all fluids every 1000 miles and just did so shy of 26,000 original miles a couple days ago. I'll see about servicing the slingers at 60,000 or more if I still own the bike then.

I never heard about doing slingers every 20,000 miles. The story I got from my mechanic was BMW was so enamored with their product-line being so superior that the engineers omitted a replaceable filter and instead placed slinger-service just around the time you might have your entire engine re-built anyway... 60 to 100,000 miles. It may be just another Vintage Urban Legend but certainly does sound very German.