Is it safe to run 20w50 oil in my TJ?

Paul Land

TJ Enthusiast
Joined
Oct 3, 2018
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337
Location
New Jersey
An Engineer/truck builder told me to use 20w50 oil i have 200k miles it sent my oil pressure gauge to 79 psi. With 10w30 i run 65psi "IS IT SAFE" My engine seems to like 20W50
But i don't need blue-smoke.
 
I would just run 10w-30 as that is what the engine was designed to run on. 20w-50 is going to put a lot of strain on the internals in the winter time. Were you having any problems with low oil pressure? If you have blue smoke, it's probably your valve seals going.
 
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It's fine to run 20w-50. Personally I'd run 15w-40 (and I do) before jumping to 20w-50 but as long as temperatures don't get too cold where you are it'll be fine. On really cold mornings your starter will struggle a bit with that stuff. Most people run really thick oil like that when the bottom end gets a little noisy when the engine is fully warmed up to quiet it down, if that's you then go for it.
 
An Engineer/truck builder told me to use 20w50 oil i have 200k miles it sent my oil pressure gauge to 79 psi. With 10w30 i run 65psi "IS IT SAFE" My engine seems to like 20W50
But i don't need blue-smoke.
The standard gold-accepted rule of thumb for good acceptable oil pressure is 10 psi for every thousand engine rpms. 65 psi was MORE than good psi. I personally would never run a 20W-anything in my TJ. 20W when the engine is cold just means that oil takes a lot longer to get circulated through the engine, especially in colder temperatures.
 
The standard gold-accepted rule of thumb for good acceptable oil pressure is 10 psi for every thousand engine rpms. 65 psi was MORE than good psi. I personally would never run a 20W-anything in my TJ. 20W when the engine is cold just means that oil takes a lot longer to get circulated through the engine, especially in colder temperatures.
Thanks J.B. You would be the one that knows.
 
20W when the engine is cold just means that oil takes a lot longer to get circulated through the engine, especially in colder temperatures.

Putting a 120v 250 watt incandescent spotlight bulb directly underneath the engine and plugging it in over night would avoid that issue. Of course I haven't seen that done on anything since winter in the early 1980s when my neighbor wanted to be able to start the Golden Jubilee to plow the driveway.
031517-Barn-Finds-1953-Ford-Golden-Jubilee-Tractor-1.jpg
 
Putting a 120v 250 watt incandescent spotlight bulb directly underneath the engine and plugging it in over night would avoid that issue. Of course I haven't seen that done on anything since winter in the early 1980s when my neighbor wanted to be able to start the Golden Jubilee to plow the driveway.
View attachment 288966
My $380.00 1983 ford Escort Diesel ran with 250w bulb till i parked over night on top of a mountain in -4 degrees. Tried to start it by pointing car down hill. At 40 MPH popped clutch and chunks of engine are still on side of that Mt,
 
That out the door, for this jeep It's been a week with 20w50 and all knocks, taps, and bangs are gone.
Keep us informed of your continued results. It would be interesting to see the results.
As for the light bulb trick I used to put a 15-25 watt bulb in the engine bay of my boat to keep condensation out but I find a magnetic heater on the oil pan places more heat where it’s needed.
 
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A work mechanic suggested I use 20w-50 for hot summer temps in Australia and I got flamed that bad I am still smouldering :)

You could be or not be the "proof in the pudding" to dispel the 10w-30 is still best in older worn TJ,s myth :)

I didnt make the change but upped to 10w 40 for winter and will go 15w 50 for mid summer, 15w-50 is for engines over 100,000 KM,s or 62,000 miles.

https://www.castrol.com/en_au/austr...oil-brands/gtx-product-page/castrol-gtx-oils.