15w40 vs 10w30 vs 5w40

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Chris142

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My new to me pickup only recomends 2 oils. 15w40 and SAE30. Gonna forget about SAE30 for now.

Would a 10w30 Diesel oil give it any better mpg? Power? It is kinda gutless w/o a turbo.

5w40? Those only come in Synthetic don't they?

Recomended OCI is 2500 miles. Personally I don't see why the currant fill of Delo 15w40 can't safely go 6-8k.
 
Originally Posted By: tpitcher
More vehicle & engine detail please...

87 F250,6.9l diesel no turbo, 4 speed with 3.55 gears. I plan on using it to take trash to the dump and dirt bikes out to the desert.
 
Sounds either a Ford IDI or a GM IDI. I have one of the former and, at least in the '86 MY, 10W30 is on the list as well. I still have all my original documentation and the big Ford Data Books for all those years. That's what I have be using on and off since the early '90s. I have not checked fuel economy between the two oils but I did check oil pressure and at about 180F, there was about 4-5 psi difference between the two IIRC. For a time, I had an oil temp gauge on the truck and, with it's oil-to-water oil cooler the oil warms up quickly but stays under about 190F in all but the most extreme circumstances.

I also had a 6.2L GM but did less testing on it re oil temps. It also had an oil-to-water cooler.

In general and IMO, engines with these types of coolers tend to avoid some of the pitfalls of an overly heavy oil, e.g. 15W40, because the oil is heated by coolant and wanms up better. that said, unless you are beating the fecal matter out of the truck in hot weather, my opinion is that you are better off with 10W30, with 5W40 next on the list. This would be especially true if the truck was going to be lightly used or short hopped.
 
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Originally Posted By: tenderloin
If you decide to use 15w40 Delvac,and don't mind rebates, Pep boys has 1 gal jugs for $10 after $5.00 mail in rebate.
Oh I have oil! Remember when O'Rileys was selling Delvac for $6 a gallon? They didn't have any here and substituted the Delo. I couldn't load up on it fast enough.

I'm down to 18 gallons of it.
lol.gif
 
In 1987 there was no 10w30 diesel engine oil. For your desert use I'd probably stick with the 15w40. 5W-40 needs to be a synthetic for the wide viscosity spread, and probably not worth the extra cost in your case--no frigid winters and few annual miles. Modern oils live longer than '87 oils, so 2500 ODI is probably short, but if the engine has much wear and is sludging up the oil, it might be a good idea.
 
Originally Posted By: friendly_jacek
10W30 diesel oil is for winter use, right?


Normally yes, but some people also use it year-round in certain applications.
 
Originally Posted By: Ken2
In 1987 there was no 10w30 diesel engine oil.


True but in 1986, according to Ford, only a CC oil was required for the 6.9L and many 10W30s of the day were SF/CC. This is the oil chart from my '86 6.9L owners manual and I ran Pennzoil 10W30 SF/CC oil in it for several years... towing in hot weather with it no less. Note "recommended" under the 10W30/10W40 line. The modern 10W30 HDEO is much better oil. Any modern oil is much better oil, but the viscosity recommendations from even that far back still hold water IMO.

After 25 years of owning this truck, many oil analysis, running all sorts of oil thru it, tearing it down and looking at the results (lower end virtually perfect after 140K miles and less than .001" taper in cylinders), I contend that 10W30 isn't detrimental to this engine. And in certain circumstances, given it's large sump, oil cooler and efficient cooling system, 10W30 may be advantageous.

That said, I don't see any issues running 15W40 and if I lived in a warm climate, had gobs around bought at a great price, I'd probably use it. My point is only that 10W30 HDEO will work just fine in this engine.

86F250DoilvischartLR.jpg
 
I agree with Jim, I have an '89 7.3 IDI that was bought new. 10w30 is all thats used in it. For a while we ran 15w40, but cold starts on these, as well as your 6.9 can be well unrefined at best. The little bit of cold crank speed with 10w30 does help.

My '89 is a Super Duty (F550) and loaded down and run down the highway, so don't think you "need" a 40wt in heat or towing, evidence, and the owners manual says otherwise.
 
Let's put things into perspective:
IIRC, Ottomatic had an old IDI Ford using monograde 30 HDEO Pennzoil. It was still running great (without ever having so much as a valve cover off), when it was stolen with 450k miles on it ...

In the OPs area (Apple Valley, CA) cold temps are not an issue; heat might be as his area "averages" 99 deg as a high in the summer. I'd run whatever you can find on sale; not going to matter much between a 30 grade or 40 grade. Multi-vis is going to help oil flow quicker upon starts.
 
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If your '86 is anything like my '89 7.3-it'll run on (and burn/leak) ANY HDEO you put in it, I'm still running that Delo 400 SAE 30 from the 99 cent sale from 5-6 years ago from AZ.
 
My '89 ran 30wt. for years before we switched to 15w40, then to the current 10w30. It hasn't ever failed to start, but the 10w30 does seem to help somewhat.

From my experience with the 6.9/7.3 IDI I see no reason whatsoever to use a 5w-40, 30/10w-30 or 15w40 will all work just fine. Economically any of the three should be atleast half of the money of any 5w-40, if not more.
 
Originally Posted By: roadrunner1


From my experience with the 6.9/7.3 IDI I see no reason whatsoever to use a 5w-40, 30/10w-30 or 15w40 will all work just fine. Economically any of the three should be atleast half of the money of any 5w-40, if not more.


Well said. This engine seems very forgiving on oil. I think it starts best on 10W30, though. I do try to plug it in for those cold mornings but can't always. It's really a great cold starter no matter what. I am running my last fill of Triple Protection 10W30 for break in (did an upper end overhaul on it recently) but will switch it over to the T-5 semi-syn, which has better cold start specs. I'm switching everything over to T-5
 
Originally Posted By: gmctodd
They are $13.37 at Walmart with the Mobil $25 rebate on 5 gal that $8.37 a gallon.


Napa has Delvac for 11 or so bucks a gallon this month as well.
 
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