70s era 20W50 vs modern 10W40

[Ray S]

Do the new formulations of oils allow for less film thickness when compared to 70s conventional oil? With an industrial 413-1 which operates at WOT for 10-20 minutes sometimes, the 1971 spec was 20W50 and regular OCI. They are low compression 400lb TQ low-speed motors that run with literally glowing manifolds on a long climb.
HPL indicated that their 10W40 should perform OK, any other thoughts?

 

[fantastic]

If it spec'd 20w-50 then stick with a 50 grade. I'd imagine that oils back then could've been pretty good for the top tier stuff but modern base oils & additive packages will be good enough for your old iron engine. Mobil makes a 15w-50 Full Synthetic that I need to try & easily available. You're probably not going to be able to get a long drain intervals on that bus to make premium oil pay off but that is your choice & money of course.

 

[Vexorg]

If these units can run modern 40 grade oil then I would bet that it is also good enough for your old 413. Is the 413 in your picture or for a different application? If the manifolds are glowing you either have a restricted exhaust or maybe the carb is jetted a bit too lean?

 

[The_Jeff]

I suspect the RV builder spec'd the 20w50 and not Dodge.

You'd want an oil pressure and temperature gauge for your next manic hill climb to get better data, see if things seem under control before going lighter, IMO.

 

[Ray S]

If these units can run modern 40 grade oil then I would bet that it is also good enough for your old 413. Is the 413 in your picture or for a different application?

It is the motorhome 413. I do have O2 sensors and checked the WOT mix, it is 10/1 - 11/1. Factory jetting on the 4150 Holley.

If the manifolds are glowing you either have a restricted exhaust or maybe the carb is jetted a bit too lean?

They aren't glowing bright, but enough to notice when you lift the doghouse. Exhaust is a new 3" flow-through.
Someone in a Mopar forum posted about the generator set 413s on Pacific air bases which ran 24/7, and the manifolds glowed bright at night. There are no seals on the sodium filled exhaust stems, so they intentionally "leak" oil.

Dave at HPL had recommended their BAS 10w50 ($16/qt):

We make an oil called BAS 10w50. We run that in world of outlaws 410 sprint cars at 900 plus horsepower. Although it is capable of racing only it is a streetable oil. That is what I would recommend.

The HP is only 265 net, but it doesn't have an oil cooler so I suspect the oil heats up even with the 180 thermostat and high-flow heads. I just don't ever want the forged crank to kiss the bearings...

 

[addyguy]

If you want a cheaper option; I can’t imagine that a full-syn 15W-40 HDEO wouldnt be up to the task…

 

[ripcord]

Mobil 1 15w-50 would be great for this.

I agree with The_Jeff about the oil weight spec being changed by the motorhome builder. In the 65 owners manual I found Chrysler specified 10w-30 for all weather use or 20w-40 where temps are consistently above 32f in the 413. Motorhomes tend to have poor airflow through the engine bay and put higher workloads on the engine which is why they wanted the higher grade.

 

[Ray S]

I agree with The_Jeff about the oil weight spec being changed by the motorhome builder. In the 65 owners manual

Was that 65 the auto 413 or the industrial 413-1?

 

[ripcord]

Was that 65 the auto 413 or the industrial 413-1?

Automotive

 

[burbguy82]

Is it normal for the manifold to be glowing? Does not seem right, like your mixture is way to rich............I could see 12 or so, maybe real high 11s.......but not 10s.

IMO that is an issue.....what is the AFR at idle warm or maybe 1\4 throttle?

 

[ripcord]

I would suspect late ignition timing more than fuel mixture. I looked it up and those 413 heavy truck engines only had about 7.5:1 compression ratio. With modern fuel, most any car of that vintage could benefit from having the distributor re-timed to bring in more advance, lower in the RPM range. I bet the timing on those industrial motors was super conservative.

 

[CleanSump]

I'd pick a good quality synthetic xW-50, as others have already mentioned.
We had them in GenSets in the desert and the exhaust manifolds glowed red/white all night. I think the Engineers just dumped standard Mil 2104C 30 weight conventional oil in them like the motorpool did in trucks and everything else. A modern xW-50 will protect the engine nicely.
They ran them on MOGAS which is pretty low octane, so advance was probably mild.

 

[Ray S]

Is it normal for the manifold to be glowing? Does not seem right, like your mixture is way to rich............I could see 12 or so, maybe real high 11s.......but not 10s.

IMO that is an issue.....what is the AFR at idle warm or maybe 1\4 throttle?

I have always understood that rich mixes run cooler... Also see CleanSump's comment

The primaries are almost stoic with #59 & #57 jets and 72, 70 secondaries (factory stagger jetted), and our 10% ethenol is 14.1:1. I intentionally have it all OEM except the 60kV ignition.

 

[Ray S]

I would suspect late ignition timing more than fuel mixture. I looked it up and those 413 heavy truck engines only had about 7.5:1 compression ratio. With modern fuel, most any car of that vintage could benefit from having the distributor re-timed to bring in more advance, lower in the RPM range. I bet the timing on those industrial motors was super conservative.

Yes, OEM was 7.5:1, with sodium filled valves and timing to run crap fuel.
I had the new electronic dizzy recurved by a dyno shop, and all-in advance is as per Mopar Performance Engine Modifications Manual iron B/RB:

Engine	Heads	Timing Specification
A	Production - Pre '89 (Iron)	35 BTDC
A	Production - '89 & Newer (Iron)	32 BTDC
A	W2 (Iron)	35 BTDC
A	W5 (Alum.)	35 BTDC
B/RB	Production (Iron)	38 BTDC
B/RB	Stage I, II, III, IV, V (Iron or Alum)	38 BTDC
B/RB	Indy (Alum)	35 BTDC
B/RB	B1 (Alum) Under 475 cu. in.	37-39 BTDC
B/RB	B1 (Alum) Over 475 cu. in., Under 15.0:1 Ratio	36-38 BTDC
B/RB	B1 (Alum) Over 475 cu. in., Over 15.0:1 Ratio	34-36 BTDC
B/RB	B1 TS	34 BTDC
Hemi	All (Iron or Alum)	35 BTDC

Engine	Total Advance
A	50 BTDC
B/RB	56 BTDC
Hemi	53 BTDC

 

[Ray S]

I'd pick a good quality synthetic xW-50, as others have already mentioned.
We had them in GenSets in the desert and the exhaust manifolds glowed red/white all night. I think the Engineers just dumped standard Mil 2104C 30 weight conventional oil in them like the motorpool did in trucks and everything else. A modern xW-50 will protect the engine nicely.
They ran them on MOGAS which is pretty low octane, so advance was probably mild.

I stick with 20-50 for now. I had heard about gensets before - problem is that there is nothing on the web about tuning or dyno results so I'm figuring it out.
Focusing on tuning the ZF 8 speed at the moment. Running HPL CC green fluid.