Originally Posted By: 440Magnum
Originally Posted By: NHHEMI
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Well, I have run 20W-50 in the following MOPAR engines from 65-76 wiith no issues...
318
340( actually my brother ran it in his 3 Darts - I never had a 340 )
360
383
440
Well, you can't really kill a Mopar with your choice of oil :-D
But the times I've tried 20w50, they just didn't respond well. Noise went up, oil *consumption* went up, and even though I only tried it on pretty tired engines, blow-by accumulation in the air cleaner went *up*. In other words, it did just the opposite of what I wanted to do with a heavier oil. Plus there's the 430,000 miles my 318 ran on 10w30 and nothing else. Just my experience
By the way- I've got a Royal Purple experiment going on. My "new" (30,000 miles since rebuild) 1966 440 is running RP 0w40 for this next interval (but the numbers-matching, never rebuilt 440 in the '69 Coronet R/T still gets Rotella 5w40!) Engine noises are a little quieter in the '66 than on Rotella 5w40, believe it or not (this engine has loose-ish HE pistons and a good bit of piston slap when cold). Oil pressure is great, although it still spikes over 90 psi if I get the revs up too much before its warmed up a little. It settles down to 80 PSI cruising and 40 psi at idle when fully hot. Probably didn't really need to build this engine with an HV oil pump, may even pull it for a standard pump at some point.
Obviously I'm not scared of the SM rating for the '66. The cam's fully broken in and will be fine. Its just the Magnum/Roadrunner repro cam, not anything really aggressive with monster spring pressures.
I always ran the 20W-50 from early July through early September during the hottest part of the year. I did a lot of drag racing with most of the engines too. Never had noise or consumption issues. I ran 10W-40 the rest of the year when the vehicles saw the road.
You know, you kill me on here with all of your MOPAR stories!
Been a long time since I had an old MOPAR muscle car. I miss those days!
At least my Ram has the HEMI and I can play with that ssome.