Amsoil??

[mrcaddy]

I have a 1994 Pontiac GA SE & a '95 C***y Suburban. The Pontiac has the 2.3 SOHC with 172,000 miles and the 'Burb has 186,000 on it's 350. I am considering changing to a synthetic oil primarily for better fuel economy. Has anyone else done so? Has it gave you any more MPG? How much? Are the costs a good trade off? On another note, is it actually unhealthy for these old engines to be switched? Thanks,Scott

[Matt95GT]

My 95 2.3 has been running conventional 5W-30 all its life. Out of necessity, I had to fill it with fully synthetic once, at around 135K miles. It was consuming the synthetic oil pretty quickly, yet I don't burn any oil using conventional. Personally I'd rather continue to run the conventional oil of the same weight rather than have to increase it with synthetic.

In my daily driver, I switched to fully synthetic around 20K miles. I did not see any measurable improvement in fuel economy.

[jonnythan]

It's not unhealthy to switch.

If your oil change intervals are in the 3000-4000 mile range, synthetic won't really provide any advantage, even in fuel economy. Amsoil was pretty much specifically designed for very long OCIs (think 10k). So if you're going for long OCIs, spring for a good synthetic (Pennzoil Platinum). If you're going for very long OCIs, spring for Amsoil.

Sometimes people see oil consumption go up when switching. If it does, go back to a conventional oil and stick to the ~3000 mile changes.

I do suggest that, whatever you end up doing, get your oil regularly analyzed by a lab like Blackstone Laboratories. Only about $20 and it's good to know how your engine is doing and how the oil is holding up for the intervals you're dealing with.

Personally, if I were you, I'd use regular ol Mobil Clean 5000, Castrol GTX, or yellow Pennzoil and change it every 3000 - 4000 miles and not worry about it.

[Matt95GT]

Personally, if I were you, I'd use regular ol Mobil Clean 5000, Castrol GTX, or yellow Pennzoil and change it every 3000 - 4000 miles and not worry about it.

X2. Castrol GTX 5w-30 + AC Delco PF-47 filter has been a winning combo for over 8 years on my 2.3L.