I'm going to be doing a lot of towing with my 302 this summer. Right now I run 10w-30, and I was told that I should use 15w-40 because of the constant hard work and load the engine will be having. Is this true? Should I switch over to it?

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90' F150 xlt 4x4 302 4-speed w/ 4.10 rear / 5th wheel
Headers/true duals 2.25" w/ 28" glasspacks coming out at 45's

 

I think I'd stay with what you're using. What's your oil pressure? If it's low, then go ahead and use the 15w40. Otherwise, stick with the 10w30. Remember, the key to rod bearing survival is a constant supply of fresh, cool oil. When you're towing, the bearings generate heat faster. In a normal non-worn-out engine, 15w40 will flow slower than the 10w30. This will allow the bearings to heat up more, heating up the oil more.

I'd suggest you stay with 10w30, but look for a dual rated diesel grade CI-4/CH-4 / SL 10w30, like Shell Rotella T, Mystik JT-8, or Chevron Delo. It'll have a better additive package than standard gasoline engine oil. It has more anti-foaming additives, higher TBN, more anti-wear additives, and more detergency. It's just "tougher" oil.

 

I agree with Rusty, Use the thinnest oil that maintains decent oil pressure.

 

Sorry, I can't agree with either of these statements. If the 10w-30 is "better" because it is thinner and flows more easily, why does Ford require 15w-40 for any towing above 50*F in the PSD? The problem with engines that are working hard is that they are getting hot, hot, hot. The oil being too thick under these circumstances is not the problem, it's the oil getting too thin. Oil pressure should be adequate at anything above a fast idle unless there is a problem with the oil pump.

I do agree that a diesel oil is better, but I would not go for an SL-rated oil. The only significant difference between the SJ and the SL is that they reduced the amount of phosphorous (ZDDP additive) that is allowed to help save the cat. So, in upgrading the oil from SJ to SL, they took out the good stuff. Yes, the CI-4 has more detergents than CH-4, but with a gasser, the CH-4 has plenty of soap in it.

I'd looked for a CI-4-CH-4/SJ-rated 15w-40 diesel oil (not an SL-rated oil) and run it when towing above 50*F.

CH-4 15w-40 is also much easier to find and there is a wide selection of house and name brands.

 

jschira, well said. I'm amazed at the number of people who decide what oil Ford "should have recommended" for use in their engine.

 

Um, it's a 302. Not a diesel PSD. Diesels dont rev as high, therefore not generating as much heat in the rod bearings. In addition, the thicker oil is more necessary in a diesel because the bearing isn't turning as fast, and the oil film has to support a higher load for a longer period of time per power stroke. The thicker oil cant get out of it's own way in the bearing as fast, and therefore supports the bearing somewhat better than 10w30 in a diesel. But we're talking about a 302, that goes down the road at engine speeds faster than the diesel, and when it really gets loaded down, it shifts and then revs a LOT faster than the diesel. The oil doesn't need to be thicker in the 302, since it doesn't have nearly the load to support as in the PSD. Anything heavier than what's needed to support the bearing just generates more heat. And that's not what you want when towing.

You want cool oil there, and the best way is to have more oil flowing through the bearing. If the oil was too thin, he would notice a drop in oil pressure at highway speed, especially when towing. If that's the case, then yes, go ahead and use 15w40.

The only reason I said SL is because that's the only one's I've seen in stores. I thought that the ZDDP limit only applied to "energy conserving" SL's anyway.

15w40 is close enough to 10w30 anyway, so if you can find it, use it. In it's defense, you will get a slightly thicker oil cushion on your bearings. Probably not enough effect any difference though.

I'm sure many people have towed things many miles with F-150's, 302's and 10w30. What did Ford recommend in '90 for 302's? Was it 5w30, or 10w30?

 

rusty70f100 had the correct answer. Assuming there is good pressure there is no resin to play oil weight games. The 302 will have a long life with 10w30. If you feel you need additional protection you can use a blend or a full synthetic.

 

I would say you are a prime candidate for Mobils new SUV oil or Delvac 1. They are the same with a trace element for ID purposes. It will be available as a 5w-40. I would put a Motorcraft filter with it and forget it for the next 8,000 miles. The stuff is close to bulletproof for high heat and viscosity stabilty.

 

Don't high-reving race engines use 20w-50 or even thicker? (this is not a rhetorical question).

Energy-Conserving oils have friction modifiers, molecules that thin out at higher revs, causing less friction. I have not seen a 15w-40 diesel oil labeled as energy conserving.

Nothing wrong with 10w-30. A good general purpose oil. It almost always will be an acceptable choice. With a 14 year old engine, a little thicker oil isn't going to hurt, and might just help.

 

I dont see how diesel dont generate the heat. What kind of diesel are you running? When I pull with our PSD I shift almost as high (3500rpm) depending on the load.

As for traveling down the road, our PSD runs practicaly the same rpms as my 302. The PSD is 5-speed with 5.14 rear (its over 5. ill have to look it up next time i drive it) The only difference is that a diesel engine is built stronger. I'm sure your right about the bearing and proper lubrication.

So what to do here? I am considering putting 15w-40 PLus 50 as it is used in almost everything we own. I could care less about energy-conservation.

Now, that I think about it, I just gonna get some diesel dual rated 10w-30. Sounds like changing brings up a lot of controvesy though. Thanks for the info guys.

____________________
90' F150 xlt 4x4 302 4-speed w/ 4.10 rear / 5th wheel
Headers/true duals 2.25" w/ 28" glasspacks coming out at 45's

 

Yes, some race engines use heavier oil. Typically, these are race engines that measure mileage in 1/4 mile increments though. Like your dragsters, that make an insane amount of power on every stroke. There, having a heavier oil is essential. The cars you see on sunday in the winston, oops nextel, cup, I think are using Xw30, if not straight 30 or lighter, because they need the most hp they can get and keep the engine alive for the duration of the race. I know they use like 5 weight for qualifying.

There are dual rated diesel 10w30's that are not rated as energy conserving. In fact, I have not seen any dual rated diesel oil that is rated energy conserving. What the energy conserving oil additives do, is thin out the oil temporarily in the bearing when under load, reducing sliding friction and increasing gas mileage. Thus, not good for an engine under constant heavy load, but good for corporate average fuel economy.

I really think we're splitting hairs though, on dual rated diesel 10w30 vs. dual rated diesel 15w40. Use whatever's cheaper. If you can get the same oil to use in your PSD and gassers, do it.

 

Ill pry just end up putting reg 10w-30 back in. I dont want to ruin a bearing or anything. I can get the 15-40 plus fairly cheap, I have about 5 buckets of half to quarter full ones somewhere around here. The stuff I got has always worked and I was just seeing if you should of could change over.

____________________
90' F150 xlt 4x4 302 4-speed w/ 4.10 rear / 5th wheel
Headers/true duals 2.25" w/ 28" glasspacks coming out at 45's

 

There are a lot more oil lubricated parts in an engine than just rod and main bearings. Why the fixation on rod bearings only for this discussion? A 1990 does not have a roller cam, so the highest stressed oil-lubricated area in that engine is the cam lobe-lifter interface. That is where the extra ZDDP in 15W-40 really helps. The much higher HTHS viscosity will also help with cylinder wear.

Jim

 

Ok, now I'm getting confused. So using 15w-40 will not wear out the bearings and will help protect against the cylinder wear?

Where do I find ZDDP 15W-40?

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90' F150 xlt 4x4 302 4-speed w/ 4.10 rear / 5th wheel
Headers/true duals 2.25" w/ 28" glasspacks coming out at 45's

 

ZDDP is the zinc/phosphate anti-wear additive used in oil, not the oil itself. ZDDP has been used since the 1930s. It's really good stuff, but the phosphorous kills cat converters, so the newer API gasser oil rating (SL), limits the amount of phosphorous that can be added, so these oils don't use as much ZDDP.

Diesels (until recently) didn't use cats, so diesel oils can have more ZDDP in them and still pass the CH-4 API diesel oil spec. CH-4 diesel oils generally will not pass the API SL gasser oil standard. Diesel oils also generally do not use friction modifiers, so they will not carry the API "Starburst" energy-conserving label.

15w-40 is just an oil weight that is usually recommended in diesels. Any auto parts store, Walmart, etc. will have 15w-40 oil, but it sometimes is off by itself grouped together with other diesel oils. Also it is common to find it in gallon/2 gallon jugs and 5 gallon buckets instead of just quarts.

15w-40 is easy to find. Everyone that sells oils sells at least 1 brand of 15w-40. Many house brands are available too.