I have a 77 250 351M it has about 20,000miles on new motor.I use it to pull my 22'5th wheel.Some say I should us just 30 W instead of a 10 30 weight.At times it is working hard going over 8,000 ft mountains.
confused So whats up Don

 

I don't think straight 30 weight will make any difference on pulling the trailer, and might be detrimental on cold starts. As long as you use regular change intervals, every 3,000 miles if you pull the trailer regularly, the multi viscosity shouldn't be a problem. If you're concerned, use a 15w-40 instead of straight 30. I don't think it's necessary though.

I would caution you that it would probably be a good idea to use one of the dual diesel/gas rated oils (Rotella, Delo, etc.) if you aren't already. On my 351M with about 15,000 miles on the rebuild, I am staying with Rotella 10w-30. With the concerns voiced concerning reduced additive packages in the SM rated oils, I don't want to take any chances on the flat tappet engine.

 

you need to head to www.bobistheoilguy.com

 

Try something like a 5w40 synthetic, if you think you need heavier oil.

 

10w30 is my preference for late 60's to 70's era engines.

 

DON, A good 10w30 oil will allow the bottom end of your engine to work noticeably easier than a straight HD 30 oil.

Towing, and climbing hills, you want your 351M-400 to work easier, not harder, correct?

Do you like your gas mileage in your truck? If so, a 10w30 will deliver peak possible MPG. 30HD oil, will knock that MPG down, if you like filling up sooner, with more trips to the gas station, then use a SAE 30HD oil. Me personally, I enjoy the best possible MPG when I add gasoline @ $2.20 -- $2.90 gallon. Maybe more maybe less where you live. But you get my point...

Good luck.

 

I have been useing 10 30 Vavaline<(spelling) sence rebuilt 3 yrs ago.Not being a machnic when you here things I want to be sure.
I'm going to stay with the 10 30. Gas here in Northern California Reg.3.09
Thanks for your reply Don

 

Seeing as how you live in nothern calif & do tow over 8k high mountains with a fairly good sized trailer, I think you could make good use of a well formulated full synthetic 10W-30.

As an example, Texaco's 10W-30 full Synthetc's flash point is up there, like 396 F, with a 5% NOACK & .093% ash, so it can take the heat of that long mountain pull, no sweat!!!!

There are some mighty good synthetics on the market to choose from.

I just found some Synthetic Havoline at "Big Lotts" for $3 qt!!!!! It's going into the Ranger & Taurus, for their spring change out.

So why not consider a good 10W-30 synthetic for your towing, it'll take the heat, no sweat!!!! lol

Just another thought or two.

 

Now I'M really confused. Here is another thing I was told. You don't want to switch from Reg.type oil to synthetic. Something to do with the oil film on the bearnings. Make sense?????
I want to do whats best for this truck.
I do have GeerVender over/under drive that make it a lot easier.
So you think I should switch? (WOW Did I open a can of worms) This is what I like about form. Any non mechanic can ask questions and get answers from guys that know.
Thanks again Don

 

All kinds of "synthetic oil" old wives tales out there.

I've heard talk about "synthetc" not sticking to metal parts as well as "regular" non synthetic "dino" oil.
So the theroy was that your engine would suffer more wear on start up, if you used "synthetic", because more would drin off the parts.

Don't think I've ever heard of a UOA that supports that idea.

Wonder why mfgrs of vehicles like Vettes & Vipers would use synthetic as factory fill, as they do, if that were so????!!!!

Some have said if you have some oil leaks or weeps, that they might get a little more "damp", because of the synthetics flow, penetrating, & increased detergency, causing those problem areas to act out more.
Or that we could have seal compatablity problems, that would cause leaks. Years ago Mobil did have some problems, but they are long gone history now.

I've not seen any problems switching from regular Havoline, to synthetic Havoline & back again, on my 99 Ranger 4.0L & 94 Taurus 3.8L & I'm ready to fill er up agan wih the Havoline synthetic I found on sale today, without any hesitation!!!!

If you choose a synthetic that is backward compatable with previous "S" service grades, you should be fine & your engine should iike it's new oil bath!!!!

I usually get between 1.8-2.2 better higway mpg, on the Ranger running between 55-70 mph & also tow mpg improvements, using synthetic 5W-30 Havoline, over their dino 5W-30.
Wasn't able to measure any "city" mpg improvements, over the two year period I used it, so I just went back to regular Havoline 5W-30, as the Ranger was rarely driven any distance on the highway, or towed any distance with it.

I wouldn't be afraid to try a good synthetic, in a backward compatable, specified service grade, for your engine. Do whatever makes you feel comfortable.

On Edit: I see in a previous post I listed a incorrect flash point value for Havoline 10W-30 synthetic, it should have been 496 F, instead of the 396 F value I posted. Danged good stuff!!!!

Just some thoughts to ponder.

 

If I was pulling something big and worried I would go synthetic for sure.
I run it in everything and it seems most auto makers are putting it in more stuff more often.

 

There are two reasons auto manufacturers use a synthetic for factory fill. In the Corvette case, it was unusually high oil temperatures due to the lack of room for an oil cooler. I dont know the Viper case.

Cars like BMW and Mercedes recommend extended OCI's, up to 15,000 miles or two years, with an oil life monitor system. Required oil changes are also included in the purchase price of the car, so non-approved oils will not be substituted during the warranty period. Most synthetics sold in the US do not meet European standards for those extended drains. I think Audi-Porsche-VW also have dealer-only oils for turbo models.

Since most American drivers and US-Japanese brand dealers seem stuck on frequent oil changes, there is no advantage for lower priced cars and trucks to have synthetic as factory fill. The GM oil life monitor system is a big step in the right direction, but how many owners and even dealers ignore it and go back to old habits?

Jim

 

I'd run 10w30 Maxlife in it. It is a great oil with a some PAO synthetic for improved properties and durability, seal conditioners to keep your seals from hardening off and causing leaks (or rejuvinate those that are hardened off), and it has about 300 ppm moly for better engine protection and lower friction. Pretty hard to beat Maxlife. I ran it 5000 miles through the rocky mountains in a motorhome with no problems at all. Doesn't sheer either.

 

I'm WAS really getting serious about switching to Synthetic,But now I was told I will need a better oil filtering system. About $180.00,Labor around $100.00 then oil and filter around $60.00.About $350. to make the switch.OUCH
Don

 

You don't need all that to run synthetic, you need all that to run synthetic forever and not change it but just sample it.

I used to run a single bypass filter (mount and hoses to install $25-30, filt $25-30) but with fuel injection I don't even run those now.
I run 20-25k all the time with no accessories.

.