quote:
By XHVI For automobile applications, the SG and SH standards are obsolete. Motorcycles with wet clutches can't handle the highly friction modified SJ and SL formulas that also meet the GF-2 and GF-3 requirements, so that's the primary reason they are not recommended for those applications. As long as an SL oil is not GF-3, it can be safely used in a wet clutch motorcycle where a SH/SG oil is recommended.
I would respectfully dis agree with that statement.
The primary reason they are NOT recommended for M/c's is the anti-wear additives are NOT enough to maintain a good barrier lubrication level. In shared crankcases like in older bikes, the Hydrodynamic shearing that takes place is more prevalent like in a gear box/rearend, thus it relies on the barrier additives to maintain less wear due to the oil shearing that occurs.
The major difference from the API SH version of oil to the SJ, is the barrier additive reduction. Of course later from SJ to SL, the overall base oil changes(flash point,pour point and such). This is why oils such as AMSOIL, Redline, Schaeffers, Torco, Motul and other M/c oils are recommended because of the higher levels of barrier additive and has nothing to do with the actual base stock. Many bikes are not moving to a more synth base stock to help reduce the effects or demands placed on the base oil due to the excessivie shearing and a lot have just redesigned so crankcase and engine oil are not shared thus reducing the requirement/demands on the oil. The seperate gearbox oil is usually installed with a gear oil instead.
The majority of base oils used in bikes are higher quality that could meet the api standards of SJ and SL except that for the higher levels of anti-wear that exceeds the SJ/SL api limits imposed for cat damage concerns.
As for the new GF-4 oils which currently are recommending a 50% drop in the ph levels which means even a bigger drop in the anti-wear additives for newer cars, will definitely not be able to be used in a bike UNLESS, the oil company uses an alternative barrier additive such as moly, then it could be considered bike friendly. BTW, Redline, Amsoil and Schaeffers all have higher levels of barrier anti-wear protection over and above the main line automotive oils and not one of those will create a clutch slippage problem. Only solid style barrier additives like PTFE and such can and will create that problem.
One after thought I want to mention... Gear oils all have higher levels of Ph/antiwear FM's. In the limited slip rearends. There are clutches that are used to keep wheels from binding up in turns. If these fm's where bad and caused problems for clutches, wouldn't you again see that to have the same effect on that as well? Just something to add to the point.
