Author Topic: Oil Letter Designations and Meanings  (Read 5078 times)

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fredgold52

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on: January 19, 2008, 11:54:01 am
Somewhere around here, or maybe it was the manual, I got the idea that the multi-grade oil for my Bullet engine should be "SG" rated.  Then I recall vaguelyreading something about the "SM" rating superceeding the "SG" rating.

OK, I understand the multi-grade thing.  ANd I understand the Synthetic Vs Non-Synth or Dino thing.  What I have no grasp of is the meanings for the letter designations.  What does SG mean and why is it important for our older style engines.

If you can't find SG, is it OK to use SM rated oil.  And BTW, what does SM mean? (besides the definition that's knocking aroiund in my head.)

Any help on this would be very much appreciated.
Fred
2006 '65' and a 200cc Stella, Indian all the way


LotusSevenMan

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Reply #1 on: January 19, 2008, 12:04:10 pm
If it ain't broke-------------------------- fix it 'till it is!

Royal Enfield Miltary 500cc  (2003)
Honda VTR FireStorm (SuperHawk) 996cc 'V' twin
Kawasaki KR1 250cc twin 'stroker
Ducati 916 'L' twin


fredgold52

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Reply #2 on: January 19, 2008, 12:20:06 pm
Very extensive write up, LSM.  But mostly it discusses viscosity and additives.  I looked a little further on the interweb and found this from Chevron:

How to Read a Motor Oil LabelWhat to Look for On a Motor Oil Label
The symbol at left is referred to as the "API DONUT". It gives you three pieces of information. API (American Petroleum Institute) Service Rating - this two letter classification identifies the vehicle fuel type and quality level of the motor oil. The first letter indicates the vehicle fuel type that the oil is designed for. Ratings that begin with an "S" are intended for gasoline engines. Ratings that begin with a "C" are for diesel engines. The second letter designates the quality level of the motor oil. The higher the letter, the more advanced the oil and the more protection it offers your engine. An SJ oil can be used in any engine requiring an SB, SG, SH, etc. oil.

So it looks like we can use SG, SH, and SJ rated oils safely.  It probably isn't that big of a thing, but I really love this engine.

2006 '65' and a 200cc Stella, Indian all the way


LotusSevenMan

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Reply #3 on: January 19, 2008, 02:44:34 pm
I think chip frying fat is rated SL (as in Slimey) so probably OK too  ;D
If it ain't broke-------------------------- fix it 'till it is!

Royal Enfield Miltary 500cc  (2003)
Honda VTR FireStorm (SuperHawk) 996cc 'V' twin
Kawasaki KR1 250cc twin 'stroker
Ducati 916 'L' twin


Vince

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Reply #4 on: January 19, 2008, 05:02:02 pm
The later standards are NOT better for all applications. Any designation SJ or subsequent    is an "Energy Saving" oil. These are designed for late model engines running very high oil pressure in very tight tolerances.The Japanese equivalent of our SAE is JASO. They designated a standard -MA- that is roughly equivalent to our older SG. This allows a much higher percentage of heavy metals and other additives that provide a cushioning effect on on gears and other areas with large clearances, high loads, and low oil pressures. Does this sound anything like an Enfield engine? Also, the very properties that make the SJ oils flow  also will cause leakage issues in older designed or older manufactured engines. I really recommend a motorcycle specific oil that meets the MA or SG specification. Not only is it better for the Enfield, it will also enhance the transmission in unit construction engines. You cannot get these oils at Auto Zone. "Safe" for motorcycles is not the same. I know it's more expensive, but your local cycle store should carry the right oil. I use Torco (in my truck too!),but any of the name brands such as Spectro, Bel-Ray, Hondaline, etc. will be fine.


BanditRE

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Reply #5 on: January 19, 2008, 06:17:45 pm
Fred, Vince is right about the energy saving oils. If you're buying 20w50 oil, it isn't energy saving and so you don't have to worry. Its the "thinner" oils that tend to be SM rated.

For what its worth. I use dino car oil, Castrol GTX 20w50 with no ill effect and change often. To each his own. Lets not start another oil discussion or oil war!
2007 Military 500ES. 2007 Yamaha Royal Star Tour Deluxe


Foggy_Auggie

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Reply #6 on: January 19, 2008, 06:48:22 pm
Vince and Bandit are right on - stick with motorcycle branded oils at bike shops.

And my dealer said go with 10W-50 instead of 20W-50.  So I use Yamalube semi-synthetic 10W-50.  Cold start up with 20W-50 has an astronomical oil pressure surge on the oil pumps.

A little more expensive but is the lifeblood of the engine.

BTW - Mobil 1 synthetic ATF for the primary case is my dealers recommendation also.

Cheers, Foggy
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fredgold52

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Reply #7 on: January 19, 2008, 11:11:05 pm
I agree, Bandit.  I know how 'oil wars' can be.  I bought two quarts of Castrol Motorcycle oil that is SG rated for topping up my oil until the first change.

We don't have an actual motorcycle shop here but there is a place that specializes in bike and atv parts and accessories.  I'll go out next week and see what kinds of 4 stroke oil thay carry.

The information in Vinces post about the heavy metals and the cushioning they provide is some of the information I was looking for.

Thanks to you all
Fred
2006 '65' and a 200cc Stella, Indian all the way


mbevo1

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Reply #8 on: January 20, 2008, 05:01:25 am
I found Castrol 4-stroke Motorcycle oil 20W50 with the SG rating at the local Wally-World Supercenter... wasn't in the automotive section, it was by the helmets and ATV stuff.  Only pennies more than the regular SM rated Castrol.  I've heard that the "older" ratings contained some anti-wear additives that MIGHT be better for the cam, flat tappet, solid lifter hardware that we have.  Those additives aren't in the current mixtures.  It probably doesn't make any difference, but I'll use it while it's available...

Mike and Stumpy in Michigan
'07 Classic - Stumpy
'10 C5 Military - Sherman


Foggy_Auggie

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Reply #9 on: January 20, 2008, 06:52:07 pm
  I've heard that the "older" ratings contained some anti-wear additives that MIGHT be better for the cam, flat tappet, solid lifter hardware that we have.  Those additives aren't in the current mixtures.  It probably doesn't make any difference, but I'll use it while it's available...

Mike and Stumpy in Michigan

You are absolutely correct.  The government mandated that oil manufacturers remove the sulfur content from engine oil additives.  And this was done quietly without public notice.

And it can make a difference in air cooled engines.  A lot of lawn mowers and other such power equipment have shorter service lives.  With some failing within the first year or two of service.

That's why I personally don't scrimp on engine oil.  I use motorcycle manufacturer branded oils for air cooled engines.

Cheers, Foggy
Diagonally parked in a parallel universe.

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