Premium Feul? Red Grille? and Thanks!

[IaBoy]

Thanks to the group for all the information. I did decide to keep my 2 SLS's and part them out. I have an ad for them in the "For Sale" section. There are a couple of great engines in these cars if anyone needs one!

I bought a 2002 Red SLS with 44.000 miles and pick it up on Saturday. Is it true I won't have to burn Premium fuel in my new one?

By the way if anyone has a red grille laying around that will fit a 2002 SLS, let me know.. I might be interested.

Steve in Iowa

[JasonA]

I bought a 2002 Red SLS with 44.000 miles and pick it up on Saturday. Is it true I won't have to burn Premium fuel in my new one?

Congratulations! I hope you enjoy your new car.

2000+ engines are optimized for regular fuel. Adding premium fuel will not enhance the performance here, since regular fuel does not degrade it (as it would slightly in a 1993-1999 engine). All you need is good ol' 87 octane.

[IaBoy]

Thanks Jadcock...

That will be nice being able to use 87 octane fuel. Yes, it is about 10 tup to 20 cents per gallon cheaper, but availability is probably more important to me. Only about 30% of the stations in my area carry Premium Fuel. So I am always looking for a BP or a station that carries Premium. So it will be nice not to have to do that.

So using Premium would not improve performance on my new 2002 SLS? How would the group compare the performance of a 1998 SLS to a 2002 SLS? I am excited to get my new car.

Steve in Iowa

[JasonA]

So using Premium would not improve performance on my new 2002 SLS? How would the group compare the performance of a 1998 SLS to a 2002 SLS? I am excited to get my new car.

Your 1998 engine was optimized (275 peak hp) using 92 octane. Therefore, if you ran 87 octane, the engine might have seen some spark knock, and retarded the timing because of it, and maybe only made 270 hp under those conditions (for example). You could have certainly used 87 octane, but for ultimate performance under every conceivable condition, 92 was recommended.

Your 2002 engine was optimized (again, 275 peak hp) using 87 octane. There is theoretically no spark knock using this octane, because the compression was lowered to 10.0:1 (from 10.3:1) and the combustion chambers were redesigned. Since there is no spark knock, and no spark retard, using 87 octane, there is therefore no advantage to putting in premium fuel.

Again, both engines are rated at 275 peak horsepower and 300 lb*ft of peak torque. Field performance should be identical, assuming the same vehicle weight. If your '02 has many more options (or a sunroof for example) that your '98 didn't have, it might be heavier, and in theory, slightly slower. But in general, the engines made the same power at the same RPM points, so the performance should be extremely similar.