Oil conundrum-how important is the zinc levels for the 259(?) oilhead-95 R1100 GS ?

[Bonz]

Nice graphic, BLS. Nice to see the evolution of oil over the years.

Since you are talking about cars in this thread, zinc levels went lower (the chart show that) shortly after the 1995 Federal Emissions Warranty law. Not a coincidence with respect to keeping catalytic converters from failing. Boron and Moly levels have been upped in many oils as the replacement for high pressure/temp areas (valve train specifically) that zinc used to be called upon to protect.

Question: How do you reconcile lower zinc content (for instance) in extended service 20,000 mile oil with the statement that more zinc only provides longer protection, not better protection like you shared? Looking at UOA's, zinc level is not being sacrificed appreciably in those oils with the long drain intervals. Saying lower zinc levels are associated with shorter lengths of protection would not seem the case. Can you share the study showing less zinc provides the same protection but a shorter interval that you are basing this from.

Back to motorcycles... For me the best oils consistently have been M1 10w40 4T and 20w50 VTwin with respect it staying in grade over 5,000 mile OCI's in a shared sump and the benefits associated with staying in grade. Not a temperature range those two won't cover in most any bike.

 

[Greasymechtech]

I'd recommend the synthetic 15w50 and 20w50 Mobil1 oils. Don't be hesitant to use a high quality oil in anything. I can usually find both at local autopart stores and walfart. So, it makes it reasonably available and sometimes affordable. The M1 motorcycle vtwin is an easy choice and the 15w50 maybe for cooler engine starts or if supply is an issue. I do not believe that the Valvoline/Castrol 20 grade motorcycle oils are that well loaded. Vaguely remember valvoline being a ~1000ppm level and not sure about Castrol. Will have to look at the voa's/uoa's some more.

The needs have never been mute so don't believe the foolishness from the service tech rep. For example, Ford's diesel spec has a higher minimum z/p level than API ck4. And, VW's new 0w20 508 has a higher z/p limit level than api sp/gf6. So, automakers do know and understand that sometimes more is needed.

BMW is on record as specifying 1200ppm zinc being required for the first oil heads and the BMW branded oil was made by Spectro for over 30 years- I am told- with the requirements in place. I can find oils with much higher levels Mobile 1 V-Twin/Amsoil V-Twin and various racing formulations and oils with much lower levels; nearly all others.

One full synthetic, Mobil 1 15-50 and 20-50 seems to hit the zinc numbers nearly right on but I am hesitant to give it a try until I get info.

A tech service rep of a very popular brand stated that the improvements in additives since '95 have rendered the need for any required zinc levels moot.....

 

[weasley]

Zinc does not deplete over time though. It goes into the engine/transmission as ZDDP and gets converted into various other molecules until it is exhausted, but is still present as a zinc species (probably zinc oxide or zinc phosphate or similar) which will still show up as "zinc" in a UOA test. And it's all a bit moot since it is phosphorus that actually does the heavy lifting.

 

[two-up]

I'd recommend the synthetic 15w50 and 20w50 Mobil1 oils. Don't be hesitant to use a high quality oil in anything. I can usually find both at local autopart stores and walfart. So, it makes it reasonably available and sometimes affordable. The M1 motorcycle vtwin is an easy choice and the 15w50 maybe for cooler engine starts or if supply is an issue. I do not believe that the Valvoline/Castrol 20 grade motorcycle oils are that well loaded. Vaguely remember valvoline being a ~1000ppm level and not sure about Castrol. Will have to look at the voa's/uoa's some more.

The needs have never been mute so don't believe the foolishness from the service tech rep. For example, Ford's diesel spec has a higher minimum z/p level than API ck4. And, VW's new 0w20 508 has a higher z/p limit level than api sp/gf6. So, automakers do know and understand that sometimes more is needed.

Two good reads coming from the Ducati community which also endorse your choice of the Mobile 1 product (which just happen to have the exact level of zinc that BMW specs for my classic '95) from the pricing cited the articles are a bit dated but most probably remain very relevant:

Motorcycle Oils vs. Automotive Oils

The Case for Using Mobil 1 15W-50 Automobile Oil in a...

Manufacturers' Recommendation Most motorcycle manufacturers recommends motorcycle-specific oil, pointing out that car motor oils have been reformulated and no longer meet the needs of motorcycle engines. Oddly enough, they usually make no distinction between the use of synthetic or...

www.ducati.ms

 

[barryh]

AND, whats up with no one making a full synthetic or even semi GL 5 80/90 gear lube for bikes-is the word -hypoid- the reason ?

BMW motorcycle gearboxes that have already been mentioned specify 80W90 GL5. Can't say I've ever seen an 80W90 synthetic gear oil but I've been using a synthetic 75W90 in mine for years. Not sure why a gearbox should need a GL5 hypoid oil rather than GL4 or for that matter the final drive which is a spiral bevel rather than hypoid, but that's what BMW specify. I don't suppose any motorcycle uses hypoid gears. Why would they when there's no need for an offset.

 

[fonecord2]

Does the heat of an aircooled engine require more zinc?

 

[hank2]

BMW motorcycle gearboxes that have already been mentioned specify 80W90 GL5. Can't say I've ever seen an 80W90 synthetic gear oil but I've been using a synthetic 75W90 in mine for years. Not sure why a gearbox should need a GL5 hypoid oil rather than GL4 or for that matter the final drive which is a spiral bevel rather than hypoid, but that's what BMW specify. I don't suppose any motorcycle uses hypoid gears. Why would they when there's no need for an offset.

My go to 80W90 gear oil for years for shaft bikes with a separate gearbox was a Valvoline 80W90 syn blend. That was a GL5. It seemed to disappear about 10 years ago. 80W90 full syn does seem to be hard to find.

A number of different older BMW gurus (not factory) used to strongly recommend GL4 only on Airhead trans and also the /2's prior to 1970. Something about the GL5 not being bronze friendly. I don't think it was as critical on the driveshaft or differential fluid. I used the GL5, as I didn't know where to source GL4 in those years. There are a few GL4's in the US. I believe that Redline had a pricey one and Sta-Lube has a less expensive GL4 in 85W90. The Sta-Lube is not synthetic as far as I know.

A very long time ago I had a front drive manual trans Fiat, a 128. Fiat emphatically insisted on a non-hypoid gear oil for the trans. I don't believe that they stated a weight. I searched and asked a lot of people as to what they used for non-hypoid gear oil. No one knew. Eventually I finally discovered that they used straight 40 weight motor oil as non-hypoid trans lube. I've been told that a 40w motor oil is approximately the same weight as 80/90 gear oil. I don't know if that's correct.

 

[two-up]

Does the heat of an aircooled engine require more zinc?

Air cooling and design I would guess-BMW puts the cylinders sideways into the air/wind others opt to put one cylinder behind the other perhaps not the best design ? but wait there's more-the early GS' (the only real ones) also have a final drive, transmission each with its own lube and topped off with a dry clutch not the much more common wet clutch which may or may not be the reason for the much higher zinc levels in all oils which are marketed as being for 'V-Twins'

Of course I will cede to the more knowledgeable members here-air cooled engines which work well are a feat of engineering which is astounding to me, weren't most allied tanks during WWII air cooled ?

 

[stu72762]

BMW is on record as specifying 1200ppm zinc being required for the first oil heads and the BMW branded oil was made by Spectro for over 30 years- I am told- with the requirements in place. I can find oils with much higher levels Mobile 1 V-Twin/Amsoil V-Twin and various racing formulations and oils with much lower levels; nearly all others.

One full synthetic, Mobil 1 15-50 and 20-50 seems to hit the zinc numbers nearly right on but I am hesitant to give it a try until I get info.

I can purchase Spectro which continues to offer two products which are still 'exactly the same' as the BMW specs either in Golden semi or Platinum 15/20-50 but 'good' pricing is either $15.00 for the blend or $20.00 for the full syn. This translates into a wallet busting diy change just slightly north of a c note, which is a bit hard for me to take and of course I wish to get the price down as much as possible depending on the risk, if any.

A tech service rep of a very popular brand stated that the improvements in additives since '95 have rendered the need for any required zinc levels moot.....

Thoughts/advice much appreciated.

I'd just get the Mobil 1 15w50...it's just great oil. I use it in everything save for my VW TDI that has a PDF...once the warranty goes out on that car and I remove the PDF...then guess what oil I'll be putting in it?

 

[two-up]

Decided to go with the Mobil 1 20-50.

Had three of the TDI Jetta's 2002/'03 sedans, and an '04 wagon (which I should have kept) all with manuals and all flawless; never used a drop of oil between changes, never showed glycol in the samples and only scheduled maint. Made quite a bit of money-drove about 250 miles a day getting .32/mile, never once got less than 57mpg.... Always used Del 1.

Hope you like yours as much as I liked the ones I had.