Thicker oil I can run in my 1996 4.0 OHV

[sebastian323]

I am currently running 10-40 in my 1996 4.0 OHV. I am wondering what is a good thick oil I can run for engine longevity. I rarely use my truck and when I do use it is to go to the junkyard to pickup parts about 2 miles from my home or to rip around on dirt roads, so I do not care about fuel economy. Would 10w-40 be a good choice of oil ? I live in Central California, and we get a few days a year below freezing where i would have to cold start at around 28 degrees F.

 

[Angie]

you might want to read and understand oil viscosity and bearings.... cheers

Bearing Clearance And Oil Viscosity Explained | K1 Technologies

The relationship between bearing clearance and oil viscosity is a delicate balance. Read on for more information on how to get it right!There are some fairly

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[rubydist]

I would not put anything thicker than 10W40 in that engine. There is no reason to do so.

 

[Blmpkn]

The best oil for longevity is whatever the manufacturer reccomends.

 

[19Walt93]

I wouldn't use 10w40, the formula hasn't ben updated for a long time and thicker oil causes more drag from the oil pump. I'd use 5w30 in it, just like I do in the 351 in my Ranger. Multi Viscosity oil isn't "multi", the viscosity is more stable with temperature changes. 5w30 for example, gets no thicker when cold than a 5 weight oil and no thinner when hot than a 30 weight. 5 weight circulates faster on startup and reduces wear. Make sure to change it at least twice a year.

 

[sgtsandman]

I would stick with whatever was originally recommended for the engine. Too thick of an oil can cause oil starvation issues when the engine is cold and cause more damage than whatever is recommended for the engine. Only in special applications would you go heavier, like racing as an example.

 

[rhekman]

I am currently running 10-40 in my 1996 4.0 OHV. I am wondering what is a good thick oil I can run for engine longevity. I rarely use my truck and when I do use it is to go to the junkyard to pickup parts about 2 miles from my home or to rip around on dirt roads, so I do not care about fuel economy. Would 10w-40 be a good choice of oil ? I live in Central California, and we get a few days a year below freezing where i would have to cold start at around 28 degrees F.

Opinions about oil on the internet are so numerous to the point of absurdity. For the most part, oil is oil - keep it clean, keep it full - and you'll be fine.

That being said, unless you're towing or racing and revving your motor to the moon out in a hot desert, a high viscosity oil in a 4.0 OHV isn't adding any more "protection". As long as you have proper oil level and pressure, the factory 5W-30 or 10W-30 will keep everything happy. If you live on a farm and have bulk 10W-40 that you use for everything else, it's not the end of the world to use in your truck too. Keep in mind though, oil viscosity isn't just about bearings, and thicker isn't always better. A thinner detergent motor oil works better in the 4.0 to flow through the tiny hydraulic lifter passages, and to keep piston oil rings clean.

This is just an anecdote (and I am not a lubricity engineer), but when I recently tore down my '95 OHV with 300,000 miles, I had the following observations.
1. Cam and main bearings were within tolerance, with no scoring or heat damage (if you would have told me 30k of wear instead of 300k, I'd believe you).
2. Rod bearings were only slightly blemised, and slightly out of tolerance.
3. Internal block and head surfaces were all clean and relatively varnish free, with a small amount of sludge in the bottom of the pan.
4. ALL (every single one) of the hydraulic lifters were siezed internally. They floated smoothly in their bores, but the internal plungers were plugged with rusty-varnishy sludge.
5. ALL the pushrods had 1/8-3/16" flat spots on the tips
6. Most of the rocker arms had flat spots at the valve tip.
7. Most of the pistons had stuck oil control rings, and plugged oil drainback passages.

If you never use the truck in freezing temperatures, then just use a name brand, high detergent, conventional (or blend) 10W-30 with an API S tag.
Change oil and filter every 3000-4000 miles. Also replace the PCV valve every couple of years.

 

[gw33gp]

Pretty much everything said in this thread is true. However, I can tell you I ran my 89 STX with a 2.9L engine for almost 200K miles using Valvoline 20W-50 synthetic oil. When I sold it to a co-worker, it still ran like new and used no more oil than it did when new. The reason I ran the higher viscosity oil was; I live in SoCal and towed my race car all over the country and much of that was across very hot desert and climbing mountains. It also did a lot of duty off-road. I worked that engine very hard and ran it at fairly high rpm to keep it in the power band.

The only times I could tell the oil viscosity was too high was when I went to the mountains to ski. Then it was only noticeable if I stayed overnight when it was very cold. The engine would crank over slow in the morning, but would always start and apparently caused no damage. My co-worker that bought it drove it at least another 100K miles with no engine problems.

I ran 5W-30 and 10W-30 Valvoline synthetic oil in my 02 Ranger with the 4.0 SOHC engine from new until I got to around 230K miles. It started getting a blinking oil pressure light at idle after a long run on an Interstate, especially when towing. I began running 10W-40 then. That helped a lot. I run a micron bypass filter and that takes about 15% of the oil flow which is not a problem until the bearings get some wear. I eventually installed a higher volume Melling oil pump and now run 5W-40 oil and have no problem what so ever with oil pressure.

For your situation, I don't think you need a higher viscosity oil. Use what Ford recommends for your engine. I think the 10W-40 would work OK too if that is what you like, but I doubt you are going to get any longer life out of the engine. I found 10W-40 Valvoline full synthetic oil was getting difficult to find. It seems other brands and conventional oil is still available in that grade though.

 

[ekrampitzjr]

In years past I tried thicker oil in various high-mileage vehicles that had oil consumption and other problems from age and miles. At best the difference was marginal. I learned and I wouldn't do it again.

On my stepfather's 1972 F-100 with a 390 FE, thicker stuff caused the oil pressure gauge to read lower than normal even at highway speeds, which was worrisome. Clearly the oil pickup and pump weren't too happy with higher viscosity, despite the wear on the engine. But that truck was in a race between engine failure, transmission failure, major electrical failure, and body failure from rust, and instead of seeing which one was going to win, we eventually scrapped the truck. (The original owner had hauled fertilizer for his farm in it, and corrosion from that stuff soaking into the metal affected everything.)

If you really think the engine "needs" 10W-40 or, goodness forbid, 20W-50, it's time for a rebuild.

 

[SenorNoob]

I tried 10w-30 in my 93 4.0 and it was ok when warm, but the first below freezing day the pump just wouldn't. Zero oil pressure. Had to get another ride to work and change it the next day. (Still below freezing. Took an hour to drain.)

 

[holyford86]

I've been running Shell Rotella T6 5w40 in mine for quite some time. much better cold weather performance than 10w40 and has good oil pressure when hot as well. I change it every 6k miles.

 

[cbxer55]

Another oil thread. Yeah! WINNING!

I've run nothing but Valvoline Maxlife 20w-50 in my 98 3.0 Ranger for 22 years. Never had a problem. I've run Mobil One 10w-40 in my 04 LIGHTNING 14 years, no problems. I run 10w-40 Mobil One in my 2007 4.0 Mustang. No problems. I run 15w-50 in both my Suzuki Motorcycles, one for 16 years. No problems.