Amsoil Series 3000

[HDMXDiesel0817]

Before I purhcased my 2500HD D/A C/C SB SLT in March of this year, I had asked Amsoil which was the recommended synthetic to use in the GM Diesel and they had said that the Series 3000 5w30 was what they'd recommend. Do any of you use this synthetic? If so, have you noticed that much a difference in performance between the syn. and regular oils? The cost does not really sway me in this, it is more for fuel economy, performance, and longevity. If you could share your thoughts with me on this, either for or against...or if you have an alternative. Also what other Amsoil syns would you recommend if any for the truck? I do not plan on using any synthetics until I crack 30K, should be a little over a year before I hit that mark. Thanks!

[MAV]

I have used the Amsoil 5w-30 in both my Duramax's. I noticed no benefit as far as fuel mileage goes. It does start easier and run smoother on cold mornings. Oil pressure comes up pretty fast. With 15w-40 it would take 5-6 seconds sometimes. I am currently running Rotella 5w-40 synthetic. Should be good for year round this way.

[Kennedy]

As per George at AV Lube, the 30w part is just too light for the shock loads of a diesel engine. I'd suggest a 40w in either a 5w40 or 15w40...

[hd90rider]

my 2 cents. I use the Amsoil 15-40 year round as i am in all 48 at any given time. I use it with the by-pass system for the long intervals between complete oil changes. Have gone 60k befor a complete change & oil test came back as "OK for continued use".I started this at 15k on the truck (now at 245k) did not notice any mileage increase, but the truck is sure smooth. smile.gif

[Russ Denman]

I contacted AMSOIL and they recommended that I use the 15W-40 because I was at that time in Albuquerque, NM. My local AMSOIL dealer talked me into using the 5W-30 saying it was a better product and that the temperatures were not as extreme as people think. There was a huge debate on this forum regarding oils and it was pointed out that the minimum shear viscosity for 15W-40 oil is 3.7. The AMSOIL 5W-30 has a shear viscosity of 3.5 while the 15W-40 is rated at 4.1. I had run the 5W-30 for 15,000 miles and replaced it with the AMSOIL 15W-40 at that point. I now have over 30K and have not noticed any difference in my trucks performance. The AMSOIL warrantee states they will back there product provided you use the product designed to meet your vehicle manufacture's specifications. GM has supposedly removed all 30 weight oils from their recommendations for the Duramax. Based on that I felt I needed to use an oil that met or exceeded the 40 weight specs, ie: 3.7 or greater shear viscosity. The 15W-40 is about $10 a gallon cheaper.