I need to know? Is 15W-40 ACTUALLY BAD for my engine?

[baycountry16]

I'll tell ya, I'm a brand new owner of my first diesel truck ( 2006 f-250 KR PSD ), and I had a close friend of mine with a 2001 with a 7.3 L recommend that I use Rotella 15W-40. So as soon as I bought the truck, I went and bought 4 gallons of this stuff and put it in my truck.

That was before I found this wonderful forum! Now that I have been on here the last three weeks for hours upon hours, it seems like everyone recommends 5W-40 synthetic. I'm a little pissed because I wish I had read about this before changing my oil. Will I be good with the 15W-40 this winter?

I've already noticed here in MD as it's gotten a bit colder that if I don't plug the truck in at night it runs like chit until the engine warms up. I can't always plug it in either. Is this due to the thicker oil? I really don't want to drain it all and re do the whole process considering I've only put a few hundred miles on since the change. Will adding some Rev-x in there help w/ the cold starts.

I just baffled on what I should do at this point with the winter approaching. Any help would be greatly appreciated

[shu873]

It will run fine with the 15w-40 if everything on the truck is up to snuff. It will start cold a little rough like you've noticed but it will start. Mine always used to fine before I went to full synthetic. Once you switch to synthetic you'll notice a world of difference though...

[justinmix]

Just curious, how many miles are on the truck? And how long do you have to run it before it smooths out?

If it just misses and chugs for the first minute after you fire it up I wouldn't be to worried about it. If it misses and has low power till you get some heat in the engine then I would start with checking FICM voltage and make sure that's good. If that checks out then I'd do injector buzz and cutout tests next.

If you do have an injector or two starting to show signs of injector stiction then Rev-x might help. For the cost of Rev-x it is worth a shot. I've had rather good luck with it on customers trucks.

What part of MD are you in? We are a MD Rev-x dealer if you need some......

[ralderman]

I'm in MD as well and run AMSOIL 15w40 without any problems. When it gets real cold the engine is rough for a little while, but that is when it is real cold and it has been sitting for a while. Your truck sounds normal, but get some gauges to give yourself peace of mind and a lot more insight to your truck.

[bfrank81]

I'm in DE and I use Amsoil 5W-30 and my truck starts on the coldest of days without issue. Of course the 58v FICM helps.

You're fine run that oil for 5K and when you dump it try something else.

[baycountry16]

Thanks for all the info. It sounds like I will be fine for now until the next oil change.

Just to answer some questions, my truck has 114,000 miles on it, just got an oasis report last week to find out that the FICM and Fan clutch were replaced 15,000 miles ago, and the EGR cooler, oil cooler, IPR Valve, and #4 & #6 injectors were all replaced about 25,000 miles ago all under warranty.

The startups even when not plugged in at night aren't that bad in the morning. It always starts on first crank, chugs a couple times for a few seconds, and then idles out loudly at first, but then fine. So far, if I let it warm up for a few minutes, it seems to be fine after that. Rather than changing the oil out right now, I think I'll just try some Rev-X and switch to synthetic next oil change

[baycountry16]

Forgot to mention, I do plan on getting an edge insight cs to monitor vitals within the next few weeks as well

[Evil Eye]

Sounds like you are on the right track.

[2006PSDSD]

I run 10w-30 dino oil during the winter, as the manual says

[a2elvis]

So is 10w40 what ford recommends to run in the 6.0L in cold climates? I would just think its too thin, no? These things are hard on the oil already.