[fastfish1967]

I know it's been discussed on here more than once but I need to know! My brother has a 2005 Dodge 2500 4x4 with a Cummins and a 6-speed manual trans. He lives in Las Vegas where as you know it gets very hot. He bought the truck new and used Rotella oil the first 5K miles and then swithed to Amsoil. He contacted and told Amsoil what he used the truck for which is moderate towing and around town use. Now I know that they didn't develop a special blend of synthetic diesel oil just for him but they did need to to know everything about his truck. They sent him the required amount of oil and their oil filter and told him to run it for 25K miles before he changed it. At 22K miles he noticed that the engine was 1 quart low on oil so he changed it and the filter. He then put 25K miles on this oil before he changed it and the filter. The oil was just as clean at 25K miles as it was when he poured it in. Amsoil also has a 100% guarantee that they will replace your engine for free if it fails because of their oil anf filter. Big diesel semi's are running 100K miles between their oil changes with the same guarantee. My brother also said that his truck ran quieter and had more power almost instantly when he used Amsoil the first time. My brother is not one to say these things if it wasn't true. Has anyone on here put that many miles on Amsoil diesel oil between changes? Sorry to be so long winded but inquiring minds gotta know!

 

[nashvillebill]

The Fluids section would probably be better for this,this is quite a contentious subject, but here's my take as an engineer:

There's two big factors at work as far as oil degradation. The first is dirt/contamination. With a good filter, sure this can be filtered out. The second factor though cannot be filtered out; this is the breakdown of the oil molecules themselves, when the molecules are sheared into smaller molecules. This can be measured by viscosity changes among other things but not necessarily by the mere appearance of the oil.

The synthetics IMHO resist shearing and degradation better than pure dino oils, BUT the Powerstrokes with their HPOP are very tough on oils. Conventional oils seem to start shearing significantly about 3500 to 5000 miles.

I see folks that have posted on here indicating they have run their synthetic oil for many thousands miles with aftermarket oil filtration, and with regular lab testing to see if the oil is still good. With oil analysis, that's OK in my opinion, but without routine oil analysis, in my opinion that's taking an expensive gamble.

Given all these factors, I have chosen to merely replace the oil and filter every 3 or 4000 miles with conventional dino oil.

 

[Oilfield_Digger]

I switched my truck to Amsoil almost a year ago and would never run anything else again. I did a flush prior to putting it in and also had 2 noisy injector poppets prior to switching. Now the truck runs smooth as ever, my truck would never start in Canada below -5c in the winter if not plugged in. Now with the 5-30 amsoil diesel it will start in -40c with not being plugged in and I get INSTANT oil pressure even while cranking. Thats just my 0.02

 

[dixieland-diesels]

I run all Amsoil fluids (not thier anti-freeze) in all of my diesel trucks and nothin else.

 

[SledDogg]

I switched my truck to Amsoil almost a year ago and would never run anything else again. I did a flush prior to putting it in and also had 2 noisy injector poppets prior to switching. Now the truck runs smooth as ever, my truck would never start in Canada below -5c in the winter if not plugged in. Now with the 5-30 amsoil diesel it will start in -40c with not being plugged in and I get INSTANT oil pressure even while cranking. Thats just my 0.02

So do you run 5-30 year round? I would assume so. I'm in Michigan where the summers get hot (3 90 degree days this month) compared to most of Canada. I'm switching to Amsoil next week and I too will do a complete system flush first as well as the Amsoil/Donaldson oil filter. I'll add the twin by-pass set-up in about a month or two.

 

[White Buffalo]

I would not recommend running any oil over 5,000 miles in your Powerstroke without doing a UOA (used oil analysis) to establish some historical records. You don't want to start running extended oil drain intervals without establishing a baseline and determining how the oil properties are holding up as you increase the drain intervals over 5K. Synthetics can be run 10K+ in some applications but the Powerstroke's HEUI Injection system is harder on oil. With a chip in a 7.3L you can easily hit 3000+ ICP and 7 times that at the injector - even higher in a 6.0L. It is quite common for 7.3L's with some Dual HPOP setups and 6.0L's to shear the viscosity down to a 30 weight oil before 5K.

I'm not saying that you will always have to do a UOA, just do them long enough to establish a history and at a point to where you feel comfortable with the results.

Not knocking Amsoil - but the Powertroke HEUI Injection system is much harder on oil than your brothers Cummins. You can do a search here or on http://www.bobistheoilguy.com and see some Used Oil Analysis reports running Amsoil in this application.

 

[MJ Racing]

I would not recommend running any oil over 5,000 miles in your Powerstroke without doing a UOA (used oil analysis) to establish some historical records. You don't want to start running extended oil drain intervals without establishing a baseline and determining how the oil properties are holding up as you increase the drain intervals over 5K. Synthetics can be run 10K+ in some applications but the Powerstroke's HEUI Injection system is harder on oil. With a chip in a 7.3L you can easily hit 3000+ ICP and 7 times that at the injector - even higher in a 6.0L. It is quite common for 7.3L's with some Dual HPOP setups and 6.0L's to shear the viscosity down to a 30 weight oil before 5K.

I'm not saying that you will always have to do a UOA, just do them long enough to establish a history and at a point to where you feel comfortable with the results.

Not knocking Amsoil - but the Powertroke HEUI Injection system is much harder on oil than your brothers Cummins. You can do a search here or on http://www.bobistheoilguy.com and see some Used Oil Analysis reports running Amsoil in this application.

I agree with WB in that I would do UOA in a 6.0L at about 5-6k miles and set a baseline with your vehicle by doing oil samples. Once you get a history going you will have set a precedence with your truck and then you could set your oil change intervals based on the UOA history. Its also a good idea once you set your OCI to do a sample when you change the oil to monitor your engines internals as much as the oil. Your looking for high wear metals, coolant, fuel dilution etc not just oil viscosity.