5W40 or 10W30 '03 6.0L, recom. please

[grappler1]

Hello, I've been reading around here for a couple of weeks, GREAT SITE!
I'm relatively new to diesels, have been tinkering with some lately.

First off I have a simple question about oils, my eyes are burning from reading everything else about FICMs ect right now lol

I'm in Houston TX, currently using Delo 15W40, I've been reading that alot of you use 5W40 and some recommend SuperDuty 10W30.
I was going to switch to the 10w30, what do you guys suggest (and maybe why?)

Thanks in advance

[MoyockPowerstroke]

If you have a 6.0L Diesel...then go with 5w-40 Synthetic...I don't think out 6.0Ls like 10w30...may not be suitable...but someone will clear that up in a minute.

[cxrxaxz]

Nobody here agrees that it is good to run 10w30 in your truck, atleast none that i have seen. I switch from rotella 15w40 conv. oil to 5w40 syn. upon recommendations on this site. All i can say is i should have done it sooner. It cured my cold start issues and made my turbo smoother and whistle more. I can go out in 20 degree weather when the truck has sit for 12-15 hours and start it up and it acts like its warm. None of that clank clank clank it used to do lol. I am a supporter now lol. They also say its fine to run year around and thats what i intend to do. I am also getting an oil bypass system so that i can go longer between oil changes to make up for the price difference in the oil.

[Squid4life]

In that warmer weather 15w40 regular or 5w40 synth from the reading I have done. I honestly haven't seen much on 10w30, but have only been reading for a few months. How many miles? how warm is in down there in Houston?

[Squid4life]

Originally Posted by cxrxaxz

I am also getting an oil bypass system so that i can go longer between oil changes to make up for the price difference in the oil.

This is what I am considering. How long between you think you can go safely?

[MoyockPowerstroke]

Originally Posted by Squid4life

This is what I am considering. How long between you think you can go safely?

I have the Amsoil setup...love it...peace of mind that I'm doing something rather than nothing...but the oil still shears at 5K (hate to say that, but its true) Nothing can change that...so I wouldn't go any further than OEM recommended 7.5K (which is what is recommended for normal driving conditions)...so you get an additional 2.5K between changes...and I use 5w40 Mobil1 HDD Synthetic. I change the Motorcraft filter every 7.5K and the bypass spin on filter every 15K.

[cxrxaxz]

Originally Posted by Squid4life

This is what I am considering. How long between you think you can go safely?

I was just planning on going 7.5k instead of the regular 5k. I dont drive my truck a lot of miles though nor do i pull heavy loads with it. I just bought it for a DD and for fun. It will cost you a little more to run this oil and do the bypass but your really protecting your investment.

[grappler1]

OK, thx for the replys thusfar.
I had seen some references here from m-chan68 about using Motorcraft 10w30 diesel oil in the 6.0L, but then I realized later I think he's in Canada...

This truck has been having some cold start issues now that we've had some cooler nights and mornings, I'm not a big weatherman, lol, lets just say probably mid 30's F.
It doesnt get much colder than that here, and when it does its only couple of days here and there.

Looks like I'll change it over to the 5W40 synthetic.
Thanks

[cxrxaxz]

Originally Posted by grappler1

OK, thx for the replys thusfar.
I had seen some references here from m-chan68 about using Motorcraft 10w30 diesel oil in the 6.0L, but then I realized later I think he's in Canada...

This truck has been having some cold start issues now that we've had some cooler nights and mornings, I'm not a big weatherman, lol, lets just say probably mid 30's F.
It doesnt get much colder than that here, and when it does its only couple of days here and there.

Looks like I'll change it over to the 5W40 synthetic.
Thanks

If the syn does not help your cold start issues you might try an oil additive. A lot of people on here does not recommend using an additive in your oil. Now having said that, over at powerstrokenation they have a big thread involving rev-x oil additive. Almost everyone that has tried it has had success with it curing their cold start problems. I have not tried it since the synthetic oil cured my problem i see no need to. Since you are new to this fourm i will also tell you that it is is recommended that you use only motorcraft fuel and oil filters. A lot of people have problems with after market products especially oil and fuel filters. When in doubt just use motorcraft cause these trucks are particular. Also would be a good idea to check your batteries since its cold now. If your batteries go low it could cause your ficm problem thus also cause your cold starts.

[Galaxie]

I went to 5/40 full syn. It is great.