Mechanic at work told me to run 10-15 k.

My truck is my daily driver for work and such. Occasional 300 mile round trips to see family.

Last time I changed my oil was in June. And I've put about 6500 miles on it.

I run royal purple 15-40

I just not sure what to believe. Maybe someone has a link to an article ?

 

Personally, I have tried the extended drain intervals with full synthetics and even added a by-pass filter to make sure that everything was super filtered to include soot/carbon.

Several guys on here do regular oil analysis on their extended drain intervals and have good results out to 15k. I think you are safer with the extended drain intervals if you don't tow much and have more of a daily driver or pavement queen.

The problem is that the oil in our trucks is subjected to 2800-3000+ PSI via the HPOP and injectors. That creates oil shear. When the engine/truck works harder due to heavy towing etc. the ICP stays higher for longer periods of time which equals a faster rate of shear. So, that 40 weight that you run will get sheared down to a 30 weight eventually. Most of the info that I have read states that it stabilizes somewhere around 30 weight which may be too thin for this generation of engine.

In this truck, that equates to noisy injectors by around 6k-9k miles. Now, due to this, I never exceed 8k miles unless on an extended trip and mostly change the oil when I start hearing more noise, usually around 5k-6k if I have been towing heavy.

Anywho, opinions will vary, and are subjective based upon usage.

 

Like the above post, i have a by-pass filter and use Amsoil filters and Amsoil 15-40 synthetic oil. I sent an e-mail to Amsoil asking them about the shearing effect on their oil. They replied that there is very little shearing and not enough to change the rating of their oil, i.e. 40 wt to 30 wt. Also as mentioned above, they recommend 15,000 miles UNLESS it is used in very dusty places or is subject to very hard use like continued heavy towing or long periods of idling. My truck has none of the above but I do do oil analysis at 5,000, 10,000, than change oil and filters at 15,000 miles. I have about 180,000 miles on the truck and every analysis has been fine.

 

I've just been running napa gold. Or occasionally KN filters. I just wasn't sure on time wise too. I do a lot of short trips to work. The stores the woods. Etc. 6 months seems like time for out with the old

 

One way to know for sure is to spend a little extra money on an analysis. I use Blackstone Labs. They charge $25 for a single analysis. Kits are free. My oil often sits for almost 2 years between changes, so it's good to know what's going on with it. I run Delo 5w-40 synthetic and run it to about 6k miles. Blackstone says I could extend the interval, but I usually change it out. Thus far at 150k miles, all my reports have been excellent, so I figure, why change things?

 

I used to do used oil analysis, with Blackstone and took my oil change intervals out to 10K and then they recommended that I cut back to 9K miles and analysis was good. I wasn't running a bypass system and I am sure they help. I even had a poster here who was working for Schaeffers at the time (WhiteBuffalo) look at my reports and all was well. I owned my truck since 64K miles, and at 150K miles my injectors had to be replaced. I would not recommend doing extended oil change intervals just based off of just used oil analysis. There is significant shearing on oil in a HEUI system due to the high pressure oil pump. Synthetic oil doesn't stand up as well to those forces as standard 15W40 does, just for the record.

 

How's that? Most sythetics on the market are just more highly refined version of the conventional oils we've been using forever. In the oil industry, "synthetic" is just another word for "over-refined". Remember the fight about the Keystone Pipeline? It would carry SynBit and Dilbit (short for Sythetic and Diluted Bitumen) from Alberta. There's no Star Trek-esque technology involved, it's just heated, refined, and processed more than regular crude, in this case because the W. Canada Select that comes out of the ground is too thick to pump.
A Group 3 Sythetic, which is the most common synthetic motor oil, is just subjected to more heat and pressure for a longer time than Group 2 and Group 1, which are "conventional" oils. Again, no Star Trek replicators or Skynet involvement here, just conventional oil subjected to heat and pressure for a more refined product with fewer contaminants. Now Group 4 and 5 synthetics, which are polyalphaolefins (4) and esters (5), are ACTUALLY synthesized, not just boiled longer. The PAO oils are polymerized alpha olefins (alkenes, or double-bonded carbons like ethylene), and the esters and benzene derived group 5 oils are made by reacting acids like carboxylic acid with and alcohol. In my mind, group 4 and 5 oils are the only true sythetics, but some group 5's don't play well with additive packages, tend to dissolve paint (ever get DOT2 brake fluid on your fender?), and don't mix with mineral oils.
This is all fairly generalized, but my point is that there's not that much of a difference between most "sythetics" and conventional oils other than the level to which they're refined.

 

Sorry. Got a little long-winded there.

 

I go 5,000 miles on my T-6. I don't like going longer because it's still plenty dirty at 5,000.

 

There's no substitution for good maintenance.


Quite a few years back I ran dual HPOP's on the old truck. Even went through that phase of trying out "Extreme ICP"..... seeing pressures of 3800+ psi. So I've put oil through some extremely severe conditions.

What I found is synthetics outperformed dino oil in terms of battling shearing and standing up to the extreme abuse. Some brands were a bit better than others, however all of them shear. Don't listen to a company like Amsoil that say theirs don't..... yes they do. I have issues with Amsoil's marketing "techniques", but that's another topic.

Anyway, I learned that with dual HPOP's the best oils made it to about 5K miles tops, some only to 3K miles. I kept the 5K mile oil change interval even when I went back to the single HPOP. I found one brand that stood out very well under that abuse and I continue to use that today in my new truck.

 

Pocket, I think all of us could benefit from your experience if you choose to share the brand.

 

Valvoline Premium Blue Extreme 5w40 held up the best for me. It's what I still use now.

 

Thank you for the info. I will check it out.

 

I've stuck with 5k interval with Synthetic. No bypass system either. My .02 is the oil change at 5k is fine by me. I'm not trying to eek out every last usable penny from my oil. I'm more interested in eeking out every last mile of the motor.

 

FYI: If anyone is considering installing a Bypass Filter and is looking at the Amsoil setup, do your research on replacement filters for the Amsoil base: size, diameter and thread count. If no other manufacturer has an equivalent, you'll be stuck using the Amsoil filters and they are expensive.

If someone has a work around, please post it.