Originally Posted By: BigCahuna
If your not using Harley's brand of oil, the manual says to us a SG rated car oil. As long as the Castrol car oil has the SG rating on the bottle, you'll be fine. Evo's aren't that picky.,,
SF and SG are obsolete auto standards and had no motorcycle specific reference to start
with... All specifications prior to SL are now obsolete and although suitable for some
older vehicles are more than 10 years old they do not provide the same level of
performance or protection as the more up to date SL and SM specifications.
The American Petroleum Institute (API) sets minimum for performance
standards for lubricants... it is split (for passenger cars) into two
catagories. S = Petrol and C = Diesel, most oils carry both petrol (S)
and diesel © specifications.
The following table shows the API specifications behind the letters...
is your oil up to date???
SG - Introduced 1989 has much more active dispersant to combat black
sludge.
SH - Introduced 1993 has same engine tests as SG, but includes
phosphorus limit 0.12%, together with control of foam, volatility and
shear stability.
SJ - Introduced 1996 has the same engine tests as SG/SH, but
phosphorus limit 0.10% together with variation on volatility limits
SL - Introduced 2001, all new engine tests reflective of modern engine
designs meeting current emissions standards
SM - Introduced November 2004, improved oxidation resistance, deposit
protection and wear protection, also better low temperature
performance over the life of the oil compared to previous categories.