From all I have read & searched, there seems to be two schools of thought regarding 460 engine oil - those using 20/50 vs 10w/30 (or similar)

Except in an old worn oil burner or an engine that is being raced, is there any real concensus over which option is better?

I'm beginning to think that there can't be a significant difference, or opinion wouldn't seem so evenly divided

 

Taking into consideration that your 460 Big Block Ford is tight, and runs normal, you can use two viscosities of oil. Choose the one which you feel is best for your situation, I am thinking of a name brand, dino oil, API SL or SM certified lubricant:

10w30: Lighter weight oil, pumps well to top of engine at cold start-up. Flows much better during cold start-up and through normal engine warm-up cycle. Lighter viscosity frees up internal friction at crankshaft and bottom moving parts of your 460. Allows engine to turn RPMs easier. Your gasoline mileage will be the best possible that your 460 can deliver, in whatever condition and state of a tuneup it's in.

20w50: Thicker oil, pumps slower when cold, to top part of the 460. At start-up and through the normal warm-up cycle. Higher viscosity adds more internal friction. Starter must work harder to turn over the thicker oil when cold as compared to a 10w30. Causes engine to turn rpms harder and slower. Gasoline mileage will drop, delivering less than top MPG the 460 can deliver. Less miles traveled per tankfull, more stops for gasoline at $3 per gallon, + or - $.30 cents...

Your choice. It's all there. Both oils will lubricate moving internal parts in the 460//. Hope that helps.

 

Use the 10w30, but a heavy duty engine oil so you get extra zddp. Valvoline VR1 Racing Oil would work also.

I ran 10w30 in my 460 motorhome the whole time I owned it from 52000 miles to 87000 miles.

 

I would read the owners manual and do what the engineers say to do.

 

Does the 20/50 not offer any higher protection (I realise initial circulation won't be as rapid)

I thought today's low viscosity oils were more for close bearing tolerance, high revving, modern engines; in contrast to 1960's designed heavier, greater toleranced engines like the 460 etc.

If I'm wrong, I'd like to know. I just want to do the best I can for this engine.

Thanks

 

Heavier viscosity oil can actually build up heat through friction from the thicker fluid. It also can't flow as fast through the oil passages and oiling holes in the crank journals. The resistance to flow showns up as higher pressure on the oil gauge. It's really back pressure from the higher viscosity fluid.

Ideally, we should pick the lowest viscosity oil that is approved for the highest temperatures we expect to encounter. But instead we pick the heaviest oil approved for the lowest temperatures we expect to encounter.

 

Danged good points Scott!!!!

With todays oil technology, using, advanced add packs & re-engineered, re-formulated, highly refined base oils, with good film strength, our lubes cetaintly aren't what they were just 10 short years ago.

Danged good point about oil pressure intrpertation too, as we often mistakenly associate it with oil flow volume & forget the viscosity factor in flow volume.

We also used to think of an oils viscosity, in terms of film thickness protection, which with todays tough thin film lubes, calls for some recalibration of our thinking.

Not saying that thick lubes aren't called for in some old applications, but with todays high revving OHC engines, a thick 20W-50 lube just might help that puppy come unraveled at the redline & at that rpm, it would likely cause our butt to tighten up to about the size of a squirrels ear!!!! lol

So I suppose we all could use a re-calbration "attitude adjustment" of our lube thinking!!!!

If we aren't sure what to do about lubrication, just dig out that great unread document called "Owners Manual" & actually read it, cause all the thinking has already been done for us by Fords lube engineers, who have spent a lifetime studdying our rides lube needs & we paid BIG bucks for that info, when we bought that new ride!!!

 

Until recently, 10W-30 was the most "universal" choice. It is even listed in the owners manual of my 1957! This thick oil thing was a result of higher temperatures from crude 1970's emission tuning and the poor performance of thinner solvent-refined oils at elevated temperatures. Straight 30 was a good summer option, because it didnt break down like the multigrades, especially 10W-40.

What might surprise everyone here is that 15W-40 is now the best selling grade. I think it is because diesels are more popular than ever and the gasoline engine oil market is split between 10W-30, 5W-30 and 5W-20. Sales of straight weights, 10W-40 and 20W-50 have fallen off a cliff in the last few years. I use 15W-40 in aircooled engine applications where I would have used 20W-50 or straight 30 in the past.

Jim

 

Ditto.
Then, all you have to do is figure out whether you want synthetic or not.

 

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You will cause more wear over a shorter period of time using 20w50, since it won't pump to the top of any engine very fast. Even in a 460/.

You're thinking is more align with dated oil technology, when oils tended to vaporize and burn off much more quickly, so the conventional thinking was using a thicker oil, will slow that phenonemon down. It worked, but there was a tradeoff.

Oil, today, has standards and additives that prevent this from happening, as compared to yesterday's oils. Modern engines were designed to run at a higher and higher normal temperature, so the oil had to be able to take those high heat conditions. Remember too, in the 80s, turbocharged engines were popular in many cars, small cubic inches but a turbo helped to make more power. Those oils had to be able to withstand high high conditions, especially during shutoff and heat soak conditions where the bearings in a turbo could bake oil causing it to break down. Again, the oil companies rose to the challenge and have come up with a much better lubricant, from dino oils, blends to full sythetics.

Unless your 460 is worn, burning oil, loose, then a 20w50 would be beneficial. Otherwise, a 10w30 oil is your best choice, absolutely nothing higher than a 10w40.

 

Did he ever post what year and miles on his 460?

Anyway, 10w30 should suffice but if older engine (like 70s) or high mileage, a good 15w40 would do nicely.

 

TallPaul

It's an 82 - the truck has been to the moon & back, but I don't know the engine year - it's not original to the truck.

The engine (and all the running gear) has done low miles since it's last rebuild.

I missed mentioning that it is LPG dedicated, so is operating at higher temps.
In view of this, I'm leaning toward a compromise of a 15w/50

 

How about RV's and boats? I know a few people who swear by 50W Valvoline racing oil in RVs and boats, saying anything else is bad?!!?

To show how ignorant I am, I thought that the thinner oils did not do so well once they got hot, and had a few miles on them. I had a 351M with about 140K on it when I bought it. I drove the snot out of that car, 3k drain intervals. I initially ran Castrol GTX 10W30 in it. With fresh oil, I noticed good oil pressure (on a manual gauge) but after 500 or so miles I noticed the pressure would not stay up like it had when the oil was new. I made the decision to move up to 10W40, noticed the same thing, then 15W40. About 20K went by, I seen that I was loosing even more pressure. Soon I was up to 20W50, and after 500 or so miles down to about 5PSI at idle, 25-30 PSI cruise, 50 when cold, only for about 2 minutes. Was the oil a possible culprit, or just a crappy engine pounding the snot out of the bearings?

Another question. I recently installed a junkyard gasser 460 with around 130K on it. I popped off a main cap, seen that there was only a little bit of copper showing, so we decided to run the engine as is. I transfered the old engines oil pump to the new used motor, (I assume it was a high volume). We dumped in 6 qts of generic wally world brand 10W30 oil, fired it up, ran it for a while, called things good. We had excellent oil pressure, around 40PSI at idle, and pegging the gauge going any faster than a crawl. Fast forward about 1000 miles, the engine develops a ticking noise, the owner does an oil change to 20W50 oil. Now the ticking noise sounds more like a rod knock at idle to about 2000 RPM. We even tried adding a quart of Lucas oil stabilizer to help quiet the knock, no luck. Is it a reasonable thing to assume that the oil might be too thick for the engine, thus making the noise happen? If the noise is not bearing tolerance related, I am gathering from what is in this thread, that the oil we have in it now is hurting the engine?

 

Seems I have heard that LPG is very clean burning, so one would expect that you are not going to contaminate the oil like you do with a gasoline engine. That would allow for longer OCIs. Now if you need something to take the heat better, well you can't bead an oil like Redline, which has ester base oil of the type that is the only base oil that can withstand the heat of a jet turbine. Redline is about $9 a quart though, so you would want to run long OCI. I'd call Redlineoil.com and ask them for advice on this application.

Other than that, any synthetic would likely be a good move if it runs hotter than a regular gasoline engine.

 

I have an 03 Chevy Silverado with 29,000 I bought new. It has an inherent engine rattle. After I changed the oil using a heavier grade (20/50) to quite the rattle, the rattle was worse. I changed it back using the recommended 5W30 only using Amsoil synthetic instead and the rattle dissappeared. Recently I thought I heard the rattle returning. Right after I noticed it, the "change oil" warning lit up.