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20-50 wt oil

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donandmax

Senior Member
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Just about everyone and all manuals suggest using 20 50 oil
in the 1500 engine. But I would assume using that grade in summer only.. And using 10W-40 in the winter. Am I correct on this or should I use 20-50 year round. I live in Colorado
Regards
Don
 
I use 20/50 year round in north Alabama
 
I'd say it's a "no harm, no foul" for 20~50 year 'round. If it were a newer ('80 and up) car mebbe, but our old lumps do just fine with Castrol 20~50 for all but truly Arctic conditions. You WANT that "cushion" in the clearances they were built to.
 
i've been running 10-40 simply because it's easier to find and that's what my two jeeps run....no issues yet! (fingers crossed!)
 
I recently read an extensive article someone linked on the MG forum about motor oil. The writer suggested running the lightest weight you can without losing oil. He suggested running a lighter weight for a few 100 miles, then checking the dip stick for oil loss. Increase the wieght until oil loss is undetectable at the stick. The advantage to running lighter oil is higher mpg and power.

However, I also just read an article that claimed the biggest weakness of the 1500 is oil cooling. So if you are not running an oil cooler, you probably better stick with 20/50 lest your oil run too thin at the bearings.
 
For a street engine in good shape, 5w30 works just fine. I run 20W50 Valvoline racing oil in my racecars. I run Valvoline regular oil in my street cars.
 
20W50 Castrol for me...oh, I've a '79 MGB that I've owned since new...a little over 100,000 miles on it now & the engine's never been opened...still running strong with no signs of stopping...still has high oil pressure....20W50 Castrol for me!
 
/ubbthreads/images/graemlins/iagree.gif

It took a "test" for a guy I know, who INSISTED "Oil's oil!" to realise there IS a difference in what we put into an engine. He was surprised when he wasn't adding between changes anymore /ubbthreads/images/graemlins/wink.gif
 
I race on 20W-50 but if the car was on the street I'd use 10W-40 in the cooler weather. Maybe even 10W-30.

My racer does not use an oil cooler.....and I have not seen the need for it in my 1500. Maybe if I was running a full-tilt race engine with 14:1 compression and 7500+ RPM. Still, my car (with 10.5:1 compression) lives at 5500 all the time and often runs in three and four hour enduros. As I see it, an oil cooler would only add weight.

By the way, my new Ford van runs 5W-20 oil.
 
Uh-huh... that 10w and 5w stuff just freaks me out... I ~KNOW~ it's FINE in the newer engines, but I'd never chance it in an old Lotus TC.
 
Jerri's C280 runs an even more unique Mobil One oil thasn 5-30 - & the factory states plainly that if any other viscosity oil goes in it, the warranty is void...new cars ar designed for that stuff

Look on the oil cap of an MG & it plainly states "Castrol 20W50'....believe the little Brit who designed that old engine knew better than me what to use so I'll not change
 
The 5W relates the viscosity of the oil when cold only. The higher number say 40 reflects a different measure of viscosity when at operating temperature. If you compared the two when measured in their test temp you would find that they have very close measures of viscosity.(Drain the oil hot once and drain the oil cold once and see.)
I will bet that you would see the rate of oil pressure rise on start-up quicker with the 5w than 10w. Your gauge will show this(I know that mine does).
The molecular structure of modern oils is far better now than when these cars and the labeled caps were built.
I don't recommend Mobil 1 for other reasons, but I do not see a problem with 5W30 oil or 10W40 or 20W50. They all seem to work well as long as you change the oil every 3000 miles.( the cap on my bugeye also says to use Shell oil. go figure)
 
Duckham's and Sternol, Energol, etc. on my caps.

5W when cold... 'k. Great for new cars designed for such. With LBC's there's still the consideration of oil galley capillary SIZES, oil pump tolerances, bearing clearances... I build my engines to the "tight" side, as I figure I'm not racing 'em (anymore), but I STILL couldn't bring myself to pour anything other than 20~50W Castrol in a Lotus 1600 Twin Cam.

Day was I'd put together an MGB 1800 GB engine and run nothing but straight non-detergent 30W Pennzoil in it, summer or winter. They'd go for 100K with NO complaints. Change oil every 3K, and they'd look BESPOKE on teardown.

I'm certain benzine ring technology has come a long way, no argument. But the engines we're running weren't designed with 5W and 10W lubricants in mind.

That's my story, and I'm stickin' to it.

<puts fingers in ears> "Naah-naah naaa, laAaAlLaaLaaa..."
/ubbthreads/images/graemlins/jester.gif /ubbthreads/images/graemlins/devilgrin.gif /ubbthreads/images/graemlins/cheers.gif
 
After much discussion with some guys at the Shell research center here in Houston I changed some of my old ideas. For years I would use nothing but a particular brand of 30W oil. Worked for me...in hind sight because I changed my oil so much. Anyway many years ago I was turned on to Valvoline racing oil by some VW racers who swore by it, said it would hold pressure better in a hot environment. Dang if they weren't right. I tested it againist the Castrol I was using at the time. 10 pounds more pressure same conditions. Hottern heck on a Texas freeway in the hard summer 120plus temp in a hotrod bugeye. Kinda stuck with it for years now 20W50 in the racer. I build my engines very tight. a thou on the mains and rods and a bit more on the pistons based on the piston material.
I race with a guy(sprite racer since the early 60's) who uses nothing but 5W30. He was convinced by some chemical engineers. His cars don't break and they last a long time. I still can't bring myself to run anything but 20W50 Valvoline racing oil. Go figure. I will try the light stuff on my next engine and let you guys know how it works. I will not stick my fingers in my ears when it come to learning.
 
I am reminded of a $50 Bugeye I bought in the late '60s.
It had a 948 that ran pretty good but was as loose as a goose.
Normally, it was "check the gas and fill up the oil".
No mosquitoes for miles when I drove than thing.
I got the bright idea of using straight weight 60W Harley-Davidson oil to cut down on the smoke(that's what they used in the old Vee-twins).
Anyway, that poor Frog wouldn't go more than 45 MPH with the 60W, plus it overheated like mad. Eventually, I put a $50 1098 in it.
Note: Most of the oil I used back then was "refiltered, used oil". You could buy it in the supermarket for about $0.59 a gallon. I don't think it was actually marked with any "weight".
 
Oh my, I new I'd get as many answers as there are guys answering this post. And sure enough I'm not to be disappointed. lol. Anyhow the reason I asked was because when I first start up the engine on a cold morning the 10-40 oil gets up to working pressure faster than the 20-50 Even though the yellow light goes out in a couple seconds my pressure gauge takes a little longer to rise to 75 psi (with 20-50) and to 55 psi(with 10-40).By the way those filters with the anti drain back valves in them are useless as I still have to wait a little for the light to go out. Not any difference between with or without the valve. With engine hot I'm showing 40psi hot(10-40) and 55 hot (20-50)Idle is about the same with either (about 15 psi) I'm pulling the engine as soon as it warms up here in the Rockies to fix a gawd awful leak probably coming from that front face seal that keeps the bottom of Lucy rust proof !
So I think I'll replace the bottom bearings while its out and also the thrust bearings..
Thanks for the input.
Regards
Don
 
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