Oil for vintage Mopars

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1,775
Location
Kingston
This isn't typical but mine has noisier valve train on anything thicker than a 30 weight. It doesn't matter if it's a 5w30 or 10w30, conventional or synthetic (only tried conventional 10w30 recently for about 1000 miles after doing a mmo piston soak over the winter when it was parked). The conventional 10w30 and synthetic 5w30 were both identical in perceived engine quietness. Basically no noise on anything 30 weight. Step up to a 40 or 50 weight and it gets noiser. Not loud, but if you're listening for it you can hear it. I don't feel like mine fuel dilutes bad for a carbureted engine (less than GDI if you can trust a dipstick sniff test) but I won't go much beyond 3k miles or 6-7 months, so 2 oil changes a year. It gets driven almost every day from mid April to mid November depending on when the weather gets better and goes bad in the fall. I figure if using a top grade synthetic twice a year keeps the 43 year old bearings from failing for another 10-20 years then it's worth it. What I'm trying to find out is if synthetic is actually better in that regard. I could run straight 30 grade for half the year if it would be better for wear.
 
Messages
28,125
Location
Regina, Saskatchewan, Canada
Originally Posted by 440Magnum
Hello, BITOG... I used to be a frequent poster/reader on here, but I've been pretty inactive for a few years and am a bit out of the loop on the current state of oils. Cutting to my question:
You're back! All the choices you listed are still reasonable. Valvoline VR-1 is always another option. The T6 would still be fine.
 
Messages
13,194
Location
Maricopa Arizona
Originally Posted by caprice_2nv
This isn't typical but mine has noisier valve train on anything thicker than a 30 weight. It doesn't matter if it's a 5w30 or 10w30, conventional or synthetic (only tried conventional 10w30 recently for about 1000 miles after doing a mmo piston soak over the winter when it was parked). The conventional 10w30 and synthetic 5w30 were both identical in perceived engine quietness. Basically no noise on anything 30 weight. Step up to a 40 or 50 weight and it gets noiser. Not loud, but if you're listening for it you can hear it. I don't feel like mine fuel dilutes bad for a carbureted engine (less than GDI if you can trust a dipstick sniff test) but I won't go much beyond 3k miles or 6-7 months, so 2 oil changes a year. It gets driven almost every day from mid April to mid November depending on when the weather gets better and goes bad in the fall. I figure if using a top grade synthetic twice a year keeps the 43 year old bearings from failing for another 10-20 years then it's worth it. What I'm trying to find out is if synthetic is actually better in that regard. I could run straight 30 grade for half the year if it would be better for wear.
Please UOA the carb'd engine. 5% fuel will be on the low end. https://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=227064
 
Messages
9,294
Location
Virginia
Originally Posted by dave1251
There was a nothing worse than "street outlaws" the people responsible for thinking of that garbage should be dunked repeatedly into a skum pool.
Why do you feel this way ? I'm rather curious.
 
Messages
1,275
Location
Fl
Originally Posted by dave1251
Keep on using the T-6 it worked this long no reason to change.
I agree with this.
 
Messages
55
Location
Michigan
I'm late to the party but FWIW (it's free advice, so probably not worth much) I think RT6 5w40 is still a good choice. I have always got good service from the synthetic 5w40 rotella in BBMs and don't think you could go wrong with it. I'm not using it at the moment only because (in part thanks to BITOG), I have stashed enough conventional to last awhile. Currently VR1 20w50 in the GTX (451 B engine I built in the early 2000s, edelbrock rpm heads, roller, etc), and I'm probably going to step down to a 30 or 40 next time I change it as I don't really think I need 72psi oil pressure. The bearings have always looked fantastic on that 20w50, though. Near stock 440 in the Polara (hp manifolds, MP .474 cam), currently 15w40 Delvac. I have owned that engine since the late 80s and reconfigured it a few times. I've also had good service with several 10w30s and SAE30s. TBH, SAE 30 conventional has historically been my go-to. Not sure I really even need multigrade since I don't operate the vehicles much below 50 degrees F, but the 10w30 conventional oils I have used (VR1, Chevron, Shell) have always worked fine. They don't really seem too finicky TBH.

5-5-19 Lapeergtx3.jpg


polara1.jpg
 
Messages
1,775
Location
Kingston
Originally Posted by dave1251
Originally Posted by caprice_2nv
This isn't typical but mine has noisier valve train on anything thicker than a 30 weight. It doesn't matter if it's a 5w30 or 10w30, conventional or synthetic (only tried conventional 10w30 recently for about 1000 miles after doing a mmo piston soak over the winter when it was parked). The conventional 10w30 and synthetic 5w30 were both identical in perceived engine quietness. Basically no noise on anything 30 weight. Step up to a 40 or 50 weight and it gets noiser. Not loud, but if you're listening for it you can hear it. I don't feel like mine fuel dilutes bad for a carbureted engine (less than GDI if you can trust a dipstick sniff test) but I won't go much beyond 3k miles or 6-7 months, so 2 oil changes a year. It gets driven almost every day from mid April to mid November depending on when the weather gets better and goes bad in the fall. I figure if using a top grade synthetic twice a year keeps the 43 year old bearings from failing for another 10-20 years then it's worth it. What I'm trying to find out is if synthetic is actually better in that regard. I could run straight 30 grade for half the year if it would be better for wear.
Please UOA the carb'd engine. 5% fuel will be on the low end. https://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=227064
I do plan to do one eventually. Do you know if the ones from Napa do a reliable fuel dilution test?
 
Messages
1,775
Location
Kingston
Originally Posted by Linctex
Originally Posted by 440Magnum
Originally Posted by Rob_Roy
Any 15w-40 HDEO will work fine in that application. No need for a synthetic.
Not needed... they lived for decades on Group II oils before I had them, after all. But after all the work I've done and the current state of the art, they're going to get synthetics anyway. No reason not to given the infrequent changes.
There is NO BENEFIT to running a synthetic in this application! NONE! None. You won't see longer engine life, better mileage, etc. etc. etc. etc. Stick with 15W-40 HDEO in the B & RB Mopar engines. There is zero reason to use a synthetic.
So still nothing to back this opinion?
 
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