What bebefits do the different weights of oil give you. I currently use Amsoil 15-40 in my motorhome (gas 460 Ford) which regularly pulls a heavy (about 8,000 lbs) enclosed trailer from sea level to 4400 ft. over the mountains then down into the desert and then back in a few days. This engine gets worked hard through the mountains. I am thinking of switching to 20-50 Amsoil racing oil which I am thinking will provide better film strength for the critical parts of the engine. The Ford owners manual says to use 5-30. I am in San Diego, so the weather is mild in winter but can get hot in the summer. What weight oil would you use??
The benefits of oil weights?
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IMHO proper motor oil weight is required for the following reasons:
(1)"thin" enough to quickly facilitate in lubricating various different moving parts during initial startup phase (thus the 5W or 10W or 0W part)
(2) thick enough during normal engine operation to suspend the moving parts (remember: oil tends to "thin" out the hotter they get) like con rod bearings, crank bearings, cam rockers, etc.
(3) enough "flow" to help carry the heat away from areas such as underside of the piston crowns, cylinder walls, etc.
In your case you shall do 2 things: (a) consider installing an engine oil temperature gauge and (b) consider installing an oil pressure gauge and use that as a monitoring tool.
With these 2 things in mind, you then opt for a motor oil that is up 1 level from the one specified by your manufacturer (e.g. go with 10W30 first and if it seems to be too "thin" , as it would display in form of a pressure gauge during motor idling reading), you may up 1 level to 5W40 or 10W40 and see how it works.
dunno much about gas 460 Ford but with 4 tones of payload, I bet ya must be working this engine real hard so you need engine oil that is robust enough to hold it's viscosity w/o excessively wearing out your rod/crank bearings, yet "thin" enough to quickly carry the heat from various different engine parts away for proper heat dissipation.
Another good way is to do UOA (used oil analysis) over the next couple of changes and if you see a dramatic increase in tin/lead in the oil, you know you need to up 1 level in your motor oil range.
(1)"thin" enough to quickly facilitate in lubricating various different moving parts during initial startup phase (thus the 5W or 10W or 0W part)
(2) thick enough during normal engine operation to suspend the moving parts (remember: oil tends to "thin" out the hotter they get) like con rod bearings, crank bearings, cam rockers, etc.
(3) enough "flow" to help carry the heat away from areas such as underside of the piston crowns, cylinder walls, etc.
In your case you shall do 2 things: (a) consider installing an engine oil temperature gauge and (b) consider installing an oil pressure gauge and use that as a monitoring tool.
With these 2 things in mind, you then opt for a motor oil that is up 1 level from the one specified by your manufacturer (e.g. go with 10W30 first and if it seems to be too "thin" , as it would display in form of a pressure gauge during motor idling reading), you may up 1 level to 5W40 or 10W40 and see how it works.
dunno much about gas 460 Ford but with 4 tones of payload, I bet ya must be working this engine real hard so you need engine oil that is robust enough to hold it's viscosity w/o excessively wearing out your rod/crank bearings, yet "thin" enough to quickly carry the heat from various different engine parts away for proper heat dissipation.
Another good way is to do UOA (used oil analysis) over the next couple of changes and if you see a dramatic increase in tin/lead in the oil, you know you need to up 1 level in your motor oil range.
Very well put, Quest. One small addition might be to also review the UOA section for 460 Fords and see if there's data that supports a general recommendation.
You are using a very good oil, presently.
The thicker version may help if there is an engine weakness, though.
Consider the legions of over the road diesels that use 15-40 with no problems. They certainly have heavy stresses on them.
The thicker version may help if there is an engine weakness, though.
Consider the legions of over the road diesels that use 15-40 with no problems. They certainly have heavy stresses on them.
another Todd, remember racing oils (and I do not know what AmSoil's offering is) may not have the additives that are required to give good long-term service, as their chemists aren't so concerned with acid neutralization, etc.
The Amsoil 15w-40 is about as heavy an oil as I'd use in this case. I actually would have started with their Series 3000, 5w-30 if the OEM recommended 5w-30. That would probably give you a little lower oil temps than you're seeing now, along with slightly better fuel efficiency.
If you want to try something besides the 15w-40, I'd consider the S3000.
TS
If you want to try something besides the 15w-40, I'd consider the S3000.
TS
Also consider that over the road diesels are made with clearances for 15w40 oils.
Another option with the HDEO's would be to consider 5W40 Shell Rotella synthetic. Excellant flow at start-up and thicker at high temp for the hard working 460. Price is very reasonable at walley world.
In certain, very high rpm, racing applications, bearing clearances & oil weight selection become important.
But this is a non-issue with most passenger vehicle engines.
Consider the fact that a 15W-40 is 17-18 cSt at 210F, full operating temperature.
Most 5W-30's will range from 20 cSt to 150 cSt in the 5-10 minutes required for the oil to reach full operating temperature.
So if the 15W-40 is too thick at 17-18 cSt, how would a 20+ cSt 5W-30 make it thru the bearing?
There may be other oils that are just as good as what you are currently using but it is difficult to imagine anything really being any better. Stick with what you are doing, you have made a very good choice.
I would be MUCH more concerned about the transmission (if it's an automatic).
Joe
I would be MUCH more concerned about the transmission (if it's an automatic).
Joe
I think you answered your own question. OPERATING TEMPERATURE.
also remember big diesels do not rely on oil splashing on components. most even have nozzles that spray oil onto the bottom of the pistons to cool them.
There is no question 15w40 oils will run in gassers, but i think a good 5w40 such as rottella or mobil1 turbo diesel, or even a good stout thick xw30 such as GC would help keep parts a little cooler inside and maybe even give him a little less fuel usage.
He is towing a large load, so the engine is working hard, so the oil temps are probably elevated. This is the perfect situation to use a thicker oil.
Startup wear is not a big issued since it is usually used for longer trips. 15W40 seems perfect.
Startup wear is not a big issued since it is usually used for longer trips. 15W40 seems perfect.
Lazy JW has identified the real problem, the transmission. Which one do you have and have you done anything, like adding a cooler and an inline filter. A temp gauge would be useful if you don't want to guess about how it's doing. The transmission is probably a good candidate for a synthetic trans fluid. Oh, and don't forget your rear end, synthetic there, too. No one wants a burnt out rear end in the middle of a vacation.
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I'll go with the oil and trans temp gauges. It probably has a big cooler on the trans. The engine may have one too.
Fuel economy alterations due to visc will probably be in the area of 0.0000023mpg +/- 2-3mpg depending on the prevailing winds.
Fuel economy alterations due to visc will probably be in the area of 0.0000023mpg +/- 2-3mpg depending on the prevailing winds.
Many OTR diesels do that with straight 30 or 40 HDEO. Wasn't multi 15w-40 designed for gasoline-diesel fleet use?
Another option would be fleet XXw-30.
Remind me again why the XW-40 oils mentioned would give better mpg and run cooler than Amsoil 15W-40?
In our area, San Diego, there are a couple of 460 Fords driving generators using propane. They have pan heaters and use Delo 30W oil. They keep accurate records, supplied by computer controls and have tried 5w-30 and 10w-30 with no changes that they could measure. Problem is that engines in vehicles live a much different life, than in a motorhome. Their only problem was when the engine would start to stumble every now and then. Turned out the rubber inlet hose to the fi was colapsing. A new tube fixed the problem. For temps the oil runs at 210F all the time. The water runs at 195F. This engine runs at 3600RPM all the time with oil pressure of 77PSI. Water pressure in the cooling system is 22PSI. All numbers are at steady state conditions. The engine runs about 6 hours a day and handles the extra loads during the day.
Pablo, the 5w40 synthetics do seem to give a little better fuel mileage in my 7.3 powerstroke i had vers the dino 15w40's
I never had the gonads to try the amsoil 5-30 oils in it.
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