API oil service classifications...

[Darth Xed]

Hi all, new member here!

Can someone tell me exactly what the API oil service classifications mean?

I went to this site:

http://api-ep.api.org/filelibrary/A...lGuide_2004.pdf

But all it really says about the Service Classifications is what years (and prior) of engines they are suitable for... but.... what is actually DIFFERENT about the oils?

I have a small 4-stroke engine in a line trimmer that calls for SAE30 oil, with a API Service Class of SJ or SL. The oil that the dealer sells and recommends themselves (even though the owners manual specifically calls for SJ or SL) is SG.

The only thing i can find is that SG is for 1993 or older, SJ is for 2001 and older, and SL is for 2004 and older....

So, is there any oil guru out there than can tell me what the difference is? Am I going to hurt the engine is I use the SG? I am pretty sure it's fine since it's what they sell, but I am at least curious about the differences now, if nothing else.

 

[Blue99]

The amount of phosphorous has been reduced thru the recent API service grades to protect the catalytic converters on gasoline engine vehicles.

This has reduced the usage of the common anti-wear additive, ZDDP, from 1200 ppm in the SH/SJ grades, to 1000 ppm for SL and 800 ppm for SM.

Most engine oils for 4 cycle lawn equipment applications are rated SH/SJ with 1200 ppm of ZDDP. Offhand, I'm not familiar with the specs for an SG motor oil.

As I recall, these 4 stroke trimmers only use about 6 oz. of oil, so I'd recommend the 20 oz. bottle of SJ Briggs & Stratton engine oil which sells for about $1.75 a bottle.