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a little disagreement with synthetic oils needing no VII (viscosity improvers)

This is an over simplification, but what you are comparing are the viscosity of the oil measured at freezing and at the boiling point of water.

The 20w (winter grade) represents viscosity of the oil measured at freezing.
The 50 represents the viscosity of the oil measured at boiling 100c 212f or whatever.

There are some synthetic oils that may have a rating of 20w20 containing no VII.

However I really doubt any synthetic oil can achieve a 20w 50 rating with no VII.

However synthetic oils contain no parafin wax so much less VII is needed than in mineral oils.

However in my career I blended fuel oils and diesel oil for viscosity, pour point etc. I never worked with motor oils so I may be on a slippery slope.
 
P. Monk -

I might have over simplified things, but there are certainly different kinds of "synthetic". I'd have to track it down again, but it sounded like being much more shear stable than mineral oil, it doesn't break down as quickly as other oils which have to be "doctored" with VIIs.
 
I might be wrong at what temp the winter viscosity is measured.

It was a long time ago that I dealt with blending oils. But you are absolutely correct that the synthetics do not require as much VII as mineral oil, and they are much more resistant to shearing than the mineral oils. So the question is, do you run synthetic oil in your airheads?

I have always been afraid to do that but I am considering trying it mainly to see if I get less oil blown into my right carb. One theory is that the synthetics do not foam like mineral oils.
 
No, I run mineral oil...I've been thinking about stepping "up" to Golden Spectro which is a semi-synthetic. I read where Paul Glaves mentioned something in the "Oil Rebranding" that if he had an Airhead today, he'd use a synthetic because of the wide temperature ranges that the engine operates in.
 
Just saw a news story about "obsolete" oil being on the shelves or stores and that it could be damage car engines. The backs of the labels say "not to be used in engines built after 1988". Hmmm...I wondered what they meant...could it have to do with the API SG/SH ratings.

http://www.pqiamerica.com/apiserviceclass.htm

Sure enough...the chart in the above link includes all oils up to the SH rating. But of course, that's generally what we need in our Airheads!

I know we love our venerable Airheads, but now we're running obsolete oil?? :banghead I hope I can sleep tonight. ;)
 
Kurt,... at the risk of re-igniting an oil thread,... I have been using Spectro Heavy Duty Motorcycle oil, 20W50, for several years. Non-synthetic and carries an API SG rating. No trouble so far.
 
James.A -

No worries using that oil IMO. I'm still getting my oil from BMW, but at some point, I'll probably track down some Spectro myself. :thumb
 
Warning. Cynicism alert.

Follow the money. The Feds mandate a 7 year warranty period for emissions control equipment on cars. That includes three-way catalytic converters. ZDDP ( a zinc phosphorous compound ) can damage catalytic converters. Replacing them under the 7 year warranty was aggravating the then "Big Three" U.S. auto makers. They badgered the API - American Petroleum Institute - into reducing the amount of ZDDP called for in the API SG rating. The first reduction happened with SH rated oil. The API said it was equal to or better than SG but of course for flat tappet engine designs - cam and follower scuffing action - it wasn't. Then they reduced the required levels of ZDDP further for SJ rated oils. The API again claimed that SJ superceded all prior ratings but that was even more untrue. For modern cars with roller cam followers and 3-way cat-cons the car makers were happy.

But for older cars and many motorcycles things were less than hunky and dorry. BMW disagreed with the API that SJ oil superceded the older standards. BMWNA Issued Service Bulletin #2855 on November 25, 1998. Among other statements was the following key statement:

"Not Approved:

The API specification SJ is not approved for use in any BMW motorcycle.
This latest API classification does not guaranty the required levels of
wear protective additives such as Calcium, Magnesium, Zinc, etc. as with
most prior API specifications."

So for Airheads, Oilheads, Classic K bikes, later flop-four K bikes, etc. obsolete oil classifications are what you want. SH is acceptable but not optimal. SG is better. You will likely find this most often in motorcycle or motorsports specific oils.
 
Unrelated, I noticed the BMW packaging changed again and doesn't appear to be blended by BP anymore (still SG rating). Maybe I'll send a sample out next time I buy oil.

"Not Approved:

The API specification SJ is not approved for use in any BMW motorcycle.
This latest API classification does not guaranty the required levels of
wear protective additives such as Calcium, Magnesium, Zinc, etc. as with
most prior API specifications."

When I got the Porsche oil tested, it was claimed I believe here and on some other forums I was looking at that "Americans are the only ones that care about ZDDP," that TSB directly refutes that. Thanks for the info.
 
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