20W-50 dino for stock '69 350 with 80K miles

[TWINRAY]

I would like to use 20w-40 but they stopped making it a while back. I was using 10w-40 but heard 10w-30 actually protects better because it has only a 20 spread in the #'s vs. the 30 spread in the 10w-40. So then I converted to 10w-30. Same article said you could have a 30 spread and have good protectdion if you start out higher than 10W.

I'm going on a straight 300 mile run and think I'd be better off with something other than the 10w-30 but 50 weight sounds too thick. I guess it's marketing because some may think 50 is better than 40 cause it's a higher #. What about straight 30. Temperature will be 60 degrees and up.

 

[cruzer99]

Run the 10-30....What you need to keep in mind is the lower number will allow better lubrication to bearings that have a close tolerance. An example is Toyota recommends 5-30 because the rods and mains are at a tighter tolerance than most other cars which is also why they get 150000-200000 miles on an engine. As engines wear and the tolerances loosen up you can and should run a higher weight oil. If you are driving normally and need 50 weight to get good oil pressure it might be time for a rebuild.

My .02

 

[JohnZ]

Forget the marketing hype and BS - 20W50 only behaves like 50-weight at extreme temperatures, and like 20-weight at low temperatures; multi-viscosity oils have been around for over 40 years now, and their superiority over "straight-weight" oils has been proven conclusively. 10W30 will work just fine. There's nothing special about Toyota engines or clearances - ALL manufacturers recommend 5W30 these days, primarily for cold-weather protection and miniscule improvement in fuel economy.

 

[drags1998]

Johns correct, 10-30 will be fine, I have gone to Mobil-1 10-30 in ALL of my Cars,Trucks,and even my JD-318 tractor. Yes, its a little more money,BUT I dont mix-up oils, And BEST of ALL, I know that im PROTECTED!!!!!!!!

 

[AKRAY4PLAY]

i am behind John as well. run the lightest oil you can and still get good oil pressure, 10 psi per 100hp is a good rule of thumb. the lighter the oil the easier it is to turn a motor. dirty oil and/or low oil pressure kill engines. change it often and SE, SF, etc. are alright to run. as Cruizer said, if oil pressure is low with heavy oil, start getting ready for a rebuild. Brian

 

[pgtr]

Add my dittos for JohnZ's comments. You will only see the SAE50 at a high operating temperature (EG fully warmed up) and that is certainly much THINNER than say SAE10 at an initial cold startup temperature...

I'll also throw in my recommendation to consider something else: 15W-40 w/ an API C spec in additon to standard current API S specs. That's awfully good oil at essentially the same price as any other conventional oil and available in an array of very good brands.

The more I have learned about 15W40 the more I like it over other common conventional oil weights. No I don't know why 15W40 isn't more widely used but I'm sold.

 

[BeaterShark]

More important that what oil vis you is use how often you change it. Everybody and their brother have been running different oils from 5w30 to 20w50 and they all swear by what they use. The difference in wear to an engine is pretty much negiligable in terms of when a rebuild will be necessary.

Also, not mentioned much when discussing viscosity to use, but I feel that climate has a lot to do with what vis to use. A xW30 at 200F has about the same viscosity as a xW40 at 220F.

As far as the 15w40s go, they are primarily a diesel oil (HDMO). They usually also meet gas oil (PCMO) specs, but they are designed for diesel engines. They also usually have a higher ash content which means more deposits on the valves and ring land than the lower ash common in PCMO oil. Whether or not the difference is negilgable, I don't really know.

 

[Culprit]

More important that what oil vis you is use how often you change it. Everybody and their brother have been running different oils from 5w30 to 20w50 and they all swear by what they use. The difference in wear to an engine is pretty much negiligable in terms of when a rebuild will be necessary.

I agree with BeaterShark - change it often.

For 90% of vehicles there's only one question to ask yourself when you're standing in the oil isle: "What oil did the smart guys with the engineering degrees design the engine to use?" They're the ones who plugged all the numbers into the equations and decided what tolerances and clearances to build the engine with.

Yes, if your engine has LOTS of miles on it, and was not taken care of early on in life (ie frequent oil changes) then you might want to consider using a more viscous oil. But chances are that by that point the engine is drinking/leaking so much oil that it doesn't really matter what you use as long as you keep it full.

I'm not a fan of changing oils - I pick one and stick with the same oil for the life of the engine - usually try to stick to the same brand also (not that it matters since any certified oil brand by definition meets the same standard).

Semper Fidelis,
Culprit

 

[TWINRAY]

10w-30 Castrol GTX is what we're going with.

 

[TWINRAY]

10w-30 Castrol GTX is what we're going with.

After 5.5 hrs and 300 miles running to 75 mph, it gave 15 lbs at idle at the end of the trip and about 36-37 at speed.