SG vs. SL (another diesel oil in gas engine question...)

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Jul 30, 2002
richmond, va, usa
I am using Delo 15w40 in a Ford 4.9 and have been in many discussions re: zinc and phosphorus levels and their effects on cats and engine deposits, but I was thinking... This is a 1992 truck that specifies an SG motor oil. I know that zinc and phosphorus levels have been dropping as formulations evolve for gas engines, but what were the zinc and phosphorus max levels for SG formulations, and how do these compare to the current levels in most diesel oils? I am wondering If I am closer to an SG with a universal HDMO than with a gas-only SL formulation? thanks, Matt
I don't think the Delo 15W40 you're using is affected by the Zinc/Phosphor content issue. So, in essence, it should still be the same. Correct me if I'm wrong here guys, Oz
I may need to re-word...I know that the Delo still has 'high' zinc and phosphorus...what I was wondering is how Delo's (or the average HDMO's) levels compare with the levels that 'old' SG oils (that my engine was designed for) have? In essence, I think that my engine may have been designed to use an oil more like Delo than an SL oil... comments, ideas, expertise welcomed! Matt
I don’t have limits for SG oils but P was limited to 1200ppm for SH oils and 1000ppm for SJ (starting 1996) and now SL. Oils over 30w are exempt. Don’t forget, theses are maximum levels. There is no minimum limit and some oils have a lot less than the maximum. The service manual for a 2002 model Honda VTR motorcycle specifies SF/SG rated oil. The VTR is a high performance sportbike so it makes you wonder how great SH/SJ/SL rated oils are?
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