I have a 1996 Z-28 that I bought new and now has a whopping 23,000 miles on it. I put Mobil 1 15W50 in it at 100 miles and have changed it every 5000 miles. No break in problems etc. I had a 1991 3/4 ton with a 350 that I put 265,000 miles on and used Mobil 1 15W50 since 500 miles after it was new and I sold it last year and it still ran great, held 60 psi oil pressure and burned no oil. BELIEVE! The stuff is great and will save You lots of cash in the long run not to count the better gas mileage savings.

 

I run Amsoil and Mobil 1 in my '99 Silverado 1500. Ihave AMS in my tranny, t-case, and rear diff. Haven't had a problem with it. Rear diffs with limited slips call for synthetic.

I went 22,000 miles between oil changes when I tried Amsoil. I had no issues and don't expect you would either as long as you change the filter every 6,000 miles and top it back off. I went back to Mobil 1 just because it is easier to get my hands on. I run it 6,000 miles sometimes and it always looks the same on the way out. I have 125,000 on my truck now.

 

As far as the cost for the Amsoil, you aren't saving any money by using the 20,000 mile oil because of the cost of the filter and the extra oil to fill the new one. If your car is still under warrenty, don't use it. If you havea problem with the motor and you take it in, they're going to ask for service records. If you change your oil at 20,000 miles it supercedes the manufacturer's recomendation of 5,000 miles. So the dealership won't honor the warrenty. Good luck trying to get Amsoil to pay for any problems. I personally haven't had any problems. I've used it in my 2001 Explorer Sport and my 2001 S10. It does stay cleaner a lot longer. I'm more of a fan of Royal Purple. Mobil one is over rated in my opinion. Each synthetic has beinifits over the other, it just depends on what you are looking for. Mobil 1 isn't the best oil to use in cars with nitrous or lose piston rings because the blow by will still dilute Mobil 1 synthetic faster than Royal Purple or Amsoil. Amsoil has better molecular tention that allows the oil to be used longer. Royal purple isn't ment to be an extended drain oil, it should be changed every 3,000 miles. It's a micro polishing oil so all the contaminats are suspended in the oil. As far as oil filters, Fram and AC delco have the same performance. I get higher oil pressure using either the K&N oil filter or the Mobil 1 oil filter.

 

I love amsoil as well. Its just a little more effort to find. My old roomate ran it in 10k intervals and went 170K miles before he sold his car with no problems.

 

Become a preferred customer and buy it straght from amsoil at 10% off

 

Synthetic is the best choice for sure. As for weight you should go with manufacturer specs and warranty requirements if you still have one. However I suggest Amsoil 10w-30 or 10w-40 depending on climate and of course you will want quality filtration. With Amsoil synthetic oil you can go 1yr/25,000mi before your next oil change. If you seek a shorter interval they have a 7500 mi XL series and if you have warranty requirements or personal preference to the standard 3000-5000 mi change interval I suggest the Amsoil OE series. You will notice cooler running temps, more power, better fuel economy, cleaner emissions and it will extend the life of your engine. For more information on synthetics and filtration visit:

http://**URL removed. PM EvansBlue f...site vendor.**

 

Hi Rod Man,

Welcome to the Chevy Forums.

I use Amsoil synthetic oil, with K&N filters. At first change I install new oil and the filter. From that point, I change the Filter only every 6000 miles. At 18,000 miles I change the oil completely. You need to top off with@ a 1/2 quart to a quart of oil when you change the filters. I check the mileage when the OLM triggers, and reset it.

My problem with Amsoil filters is they have no grip edges, being completely smooth, and they tend to back off and leak.

Many folks also swear by Mobil1. I would use their change frequency recommendations in that case.