As Jason said, the API Service Category is updated with new specifications every couple of years. All service categories are completely backward compatible, and SL is said by API to be correct for all older requirements.
I like Amsoil's line of synthetic oils and I have had good luck with them in my old F150. Stayed clean, ran quiet and i did notice a difference overall.
I have a 98 Ranger with 41K miles on it. Before too long I should change it. I would like to switch it over to Amsoil, it's been running on dino sice new according to the previous owner. Is it too late to go with synthetic or just stick with whatever works???
Do I need to worry about this??? I know some veichles specify what API service to use in there engines, such as for example SF, CJ, etc... Is this something I should be concerned about????? Tks everyone
The major importance about the API service designation is that there -be- one, at least to the "Sx" designation called for in your owner's manual. A "Cx" designation applies for diesel engine use, and has no intrinsic advantage for use with a gasoline engine. Ironically, my 2003 Hyundai 2.7 liter V6 calls for API service SG or SH... (Is South Korea on the same timeline as the rest of the industrialized world?)
I tried Amsoil's flush in one of my cars. It worked great, the amount of gunk that came out was astounding. I didn't have any head gasket issues at all and the car was flogged mercilessly. That said, I'm wary of using those type of products on a car that's been neglected. Too much cleaning too fast. The last car I switched to synthetic had 130k on it. I just swapped it in and changed the filter 1000 miles down the road (oil looked black and nasty) added a quart, ran another 1k and changed the oil and filter. Engine is much cleaner now based on how it looks under the valve cover.
I'm convined now, I havn't posted much but as of now I'm sold on synthetics, phuck what the manual says. My truck isn't under warranty. I'm gonna get me some Auto-Rx, Amsoil 5w30, and the bypass kit. Tks everyone