GSDunk
TYF Newbie
- Joined
- Apr 23, 2017
- Posts
- 25
- Reaction score
- 15
I recently became the owner of a 2003 SLT and after reading quite a few posts discussing oil changes and what is best for these 5.3 's, I decided on Mobil 1 full synthetic and a Fram synthetic oil filter.
Well after 700+ miles on the new oil, I am now completely sold on synthetic and will never use anything else ever again.
The Yukon seems to run better and better every time I drive it and with only 130000 miles on a very well maintained vehicle, the damn thing now runs like it just came off the lot and so quiet at idle that with the windows rolled up, sometimes I can't tell if the engine is even running. And just cruising at 65-70, the 5.3 is barely working up a sweat (around 2000-2100 RPMs) and is as quite and smooth as most luxury sedans.
This may be completely false, but It seems to also have an extra horse power or two.
As it was before, engine response is instant with throttle pressure but now seems just a tad quicker.
My fuel numbers have gotten slightly better and seem to be improving. The first 150 mile run I made on the new oil, I got 18.4, then I did the exact same route yesterday and got 19.7 (the route includes a few rolling hills, a small 800 foot grade and then back down the hill where 80% of the trip is on flat freeway.
With cruise control set at 67 mph on flat freeway, instant economy fluctuated between 22-24mpg. But when I set cruise to 72 mph, instant economy drops to 18-20....even though RPMs are fairly similar.
My average economy before the synthetic oil was 12.7 and now as I check it while typing this it reads 14.1
90% of my driving is city driving where the stop lights aren't timed, and each Lane on every block are covered with manholes sunk down 3-4 inches from years and years of repaving and just waiting to destroy your beautiful truck.
And if you guessed I must live in San Jose, you would be correct. Worst city streets in California.
Well after 700+ miles on the new oil, I am now completely sold on synthetic and will never use anything else ever again.
The Yukon seems to run better and better every time I drive it and with only 130000 miles on a very well maintained vehicle, the damn thing now runs like it just came off the lot and so quiet at idle that with the windows rolled up, sometimes I can't tell if the engine is even running. And just cruising at 65-70, the 5.3 is barely working up a sweat (around 2000-2100 RPMs) and is as quite and smooth as most luxury sedans.
This may be completely false, but It seems to also have an extra horse power or two.
As it was before, engine response is instant with throttle pressure but now seems just a tad quicker.
My fuel numbers have gotten slightly better and seem to be improving. The first 150 mile run I made on the new oil, I got 18.4, then I did the exact same route yesterday and got 19.7 (the route includes a few rolling hills, a small 800 foot grade and then back down the hill where 80% of the trip is on flat freeway.
With cruise control set at 67 mph on flat freeway, instant economy fluctuated between 22-24mpg. But when I set cruise to 72 mph, instant economy drops to 18-20....even though RPMs are fairly similar.
My average economy before the synthetic oil was 12.7 and now as I check it while typing this it reads 14.1
90% of my driving is city driving where the stop lights aren't timed, and each Lane on every block are covered with manholes sunk down 3-4 inches from years and years of repaving and just waiting to destroy your beautiful truck.
And if you guessed I must live in San Jose, you would be correct. Worst city streets in California.
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