Howdy, just changed to full synthetic on our '02 F250 and '01 Excursion. How long between would y'all recommend between oil changes ? I was changing at 5K religiously when using conventional. Thank you !!

 

A lot is what you feel comfortable with, I personally have run several oil analysis reports on my oil and have adjusted my change interval accordingly. Many will tell you, and I agree that 7,500 is a comfortable number, with many, including myself going over that, armed with the right info and data behind me

 

It depends. I would still do 5K. Full synthetic doesn't stand up to shear very well, but you could take a sample at 5K miles and send it off for analysis at Blackstone or other labs. Schaeffers has their own lab. They will tell you how far you can extend your oil change intervals.

That being said, I did used oil analysis using mostly Blackstone, but a few times with Schaeffers as well. Blackstone had me out to 9K miles on conventional Shell Rotella T, then I switched to Schaeffers full synthetic and it didn't stand up as well for extended oil change intervals so I had to back it down to about 6500 or 7000 miles iirc. My injectors went bad at 155,000ish miles....

I owned the truck since it had 64K miles and took very good care of it. By the looks of it, so did the previous owner. It was in show quality when I bought it, you could eat off the underside, I swear. So I am assuming he followed a regular oil change interval. I believe my premature injector failure is at least partly due to extending my oil change intervals.

 

Before I installed my Oil Bypass kit i was doing 8k miles oil changes with a filter change at 4k...I pushed it to 10k once but the injectors got noisy. I am curious how the bypass system may affect that interval...however if you listen to alot of guys on here its not really the dirtiness but the shear forces on the oil that gets us.

 

old green gets the oil changed at the same time it gets its annual inspection.

that puts it between 5-7k, and as stated in another thread, the oil still looks new.

 

I have to agree that oil shear, 40 weight gets sheared down to 30 weight, is more of the determining factor than mileage. If you are towing heavy a lot the oil will shear faster due to higher sustained ICP. If it is a daily driver that doesn't tow then it is less of a factor.

I had no luck either with Schaeffer's or Amsoil; they shear fast. The Rotella's were better especially T6. Mobile1 Turbo Diesel 5-40 was even better than T6. The best, IMO, is Valvoline Premium Blue Extreme 5w-40. After pulling 11-14k lbs. almost daily after 5k miles with VPBE there is very little extra noise from the injectors and the oil is still relatively clean.

 

I still go 5K on the Synthetic, it's easy to remember don't have to keep a journal or crawl under and look at the mileage I scribbled on the filter...but that's just me.

 

Using a Synthetic does not allow longer times between Oil Changes in any application.


However, with the adding of a filtering system and regular analysis the times between oil changes does increase.


The Rule of thumb is 25 Hours = 5,000 Miles. And, 5,000 miles is about as far as one would want to go with a HEUI System in a 7.3L or 6.0L.


Not only is the oil exposed to the lower end of the engine but also has to go through a beating in the HEUI System.


Much information can be found here: Used Oil Analysis - Bob is the Oil Guy - Bob is the Oil Guy


Personally, I change mine annually in (January). I do this as I get the best cold weather starts in February and March if you can call 30*F Cold? That's about 10k. And, every July I get an analysis done along with all my vehicles. None have showed anomalies in 10+ years.


In August I often (every few years) indulge in the Sturgis Motorcycle Rally in the Black Hills towing a 10k Trailer. And, I do have it changed on the way home of a 5,000 mile leg. I take the Filter (Motorcraft 1995) and 4 Gallons of oil with me and stop ion one of those Jiffy or Pennzoil Lube places. Oh, and a Filter Wrench as the last place broke three of theirs trying to get a filter off. They said it was over tightened. I never go more than 1/4 past tight.

 

I did that once in Florida and they stripped out the threads on my pan. Didn't say anything to me but I noticed a lot of discussion going on under my truck with a guy who looked like he was in training. And it took them forever. I was still unaware of the stripped threads until my next oil change on the other side of the country when I found the self tapping plug in my pan.

 

5000 miles. I went almost 6000 miles on my last oil and could tell the engine was happier after I changed it.

 

This part I'd like to comment on.

I ran a Terminator twin setup for about 3 years on my truck. During that time I tried different oils. Having dual HPOP's doing twice the amount of damage to oil really brings things to light.

Not once did regular dino oil ever hold up as well as synthetics.

Out of all the synthetics I ran, the Valvoline Premium Blue Extreme held up the best.

I never ran AMSOIL or Royal Purple or any of those outrageously expensive brands.

Basically all the dino oils would start having the consistency of water shortly after 3,000 miles. The synthetics for the most part would hold up to around 5,000 miles. The Valvoline could make it longer than that, but I never went more than 5,000 miles except for once on a long trip I ended up putting over 6,000 miles on the oil. It still held up. However I typically changed it with far less than 5,000 miles on the oil.

Don't get me wrong, just because a person switches to synthetics doesn't mean that it's an automatic extension between oil changes. I've never been a fan of extended oil changes, regardless of having a bypass, testing with Blackstone, etc. The engineers who designed and built the motor know way more than I do. Yeah maybe somewhere along the way Ford shortened the interval for warranty purposes, but that's fine with me. That's why I always took it to the maximum recommended 5,000 mile interval when I was running the single pump. When I had the twin pumps, I found myself changing oil way more often than that.

 

This question pops up every now and then and the responses will be all over the place. The only way to be sure is to have the oil tested. I have sent samples to Blackstone at 10k and 15k and they have been fine with my setup. If you make changes to your "routine" driving that you base your change interval on, you may want to send in a few samples to see if that limit has changed. Now that I pull my trailer more often, I am going with a 10k interval.

 

Wow, my oil is starting to look pretty black by 1K. I just assumed that diesels were dirtier and never paid much more attention. I change mine annually which for my just pulling usually to local beaches, is between 2.5 and 5K. I use Rotella 15-40. When I got the truck in 2007, I ran a couple of blackstone tests annually just before I changed the oil and there were no problems so I haven't visited the issue recently.

 

"I change my oil every 1,000 miles. I've done so since my model T and never shot a rod!" (funny how some of these guys prove their point with a negative). You may get the same result changing oil at 500 miles!

As others have said-- after testing the oil I've pushed M1 15w40 to 10k and Blackstone told me to go further. I stopped having it tested and kept going to 10k with no downsides.

 

I do 5K for reasons mentioned above (shear and easy to remember). Like Pocket mentioned, running higher ICP levels really lets you know how important that shear factor is - and I've limited the ICP levels to 3000 PSI as an agreement between my tuner and I. One thing not really mentioned clearly here - soot. The black oil comments touch on it, but I have some thoughts on this to add a little "grit" to the conversation.

Exhaust gets into our oil - plain and simple. When the engines were new, maybe not so much - but after enough years and miles, consider this:



That's exhaust gasses and soot oozing through the valve guides and seals into my oil. Multiply that by eight, by exhaust pressure on the highway vs. idling in the driveway, and highway RPMs - and that's not an insignificant amount of abrasive soot tainting our oil. Now... send that Soft Scrub from the dark side into our HEUI injectors under high pressure, and I'd be hard-pressed to encourage anybody to "save a few bucks" by extending the oil change intervals.