ROTELLA 15W 40 Oil

The Master Cylinder said:
15w40 is only "thin" when the oil is cold which is a good thing because it flows to the bearings faster at start up. 15w40 oil doesn't stay at 15 when the engine warms up. When the engine is at operating temperature it is 40.
Click to expand...



No harm meant , I know that with multi viscosity oils that the only time that the low number is used is when the oil is cold . Thin oil flows quicker .Usually a cold engine will have more clearance than a hot engine and can be subject to knocks at start up . It doesn't get very cold where I live . I would prefer 20W for cold flow here .. Quick flow isn't the only thing that is important . I feel that more viscosity to a point will better cushion the bearings . The owners manual recommends 20W in winter and 40W in summer . 20W 40 would be ideal . I feel that 50w would be good for older engines with some wear . I feel that most engines over 85 years old will have some wear unless they have been rebuilt recently . I use 20W50 and it seems to work well for me .
 
Multi-vis oil doesn't really change viscosity. A 10W-30 flows like a 10 weight/viscosity with the film strength of a 30.
 
Patrick L. said:
I figured. There are some that think the oil thickens as it warms. I don't know where that came from.
Click to expand...

Oil certainly doesn't thicken when warm-hot . Thinner oil does flow better than thick oil . Fifteen is the low number and hence the thinner of the two numbers used in a 15W40 multi viscosity oil . Just about any oil can work , even burnt oil . Being as the owners manual recommends 20W for winter and 40W for hotter temps . My point is that 15W oil is simply thinner than the oil that Ford recommended . Though oils have improved because of additives . I figure that Weight still means the same that it ever meant . A thicker oil cushions the bearings better . Oil thins with heat . Fifteen W oil is the thinner of the two numbers and will flow better . Flow isn't the only thing that is important .
 
Purdy Swoft said:
Oil certainly doesn't thicken when warm-hot . Thinner oil does flow better than thick oil . Fifteen is the low number and hence the thinner of the two numbers used in a 15W40 multi viscosity oil . Just about any oil can work , even burnt oil . Being as the owners manual recommends 20W for winter and 40W for hotter temps . My point is that 15W oil is simply thinner than the oil that Ford recommended . Though oils have improved because of additives . I figure that Weight still means the same that it ever meant . A thicker oil cushions the bearings better . Oil thins with heat . Fifteen W oil is the thinner of the two numbers and will flow better . Flow isn't the only thing that is important .
Click to expand...

The "W" in 20W, etc., stands for "Winter" not "Weight"!
 
What the 'W' means is the oil flow rate at cold temps. In other words a 10W-30 flows like a 10W at cold temps but has the film strength of a 30W.
 
I am happy with 20-50 racing oil with zinc from Napa. Ah the good ole oil debate. Do
you all remember; example my new 1975 F250 with strict instructions to only use Ford 300
motor oil or the or the warrantee will be revoked. Lets be logical, Ford Motor Co. is not
in the oil refinery business. No doubt oils, lube whatever most likely goes to the lowest
bidder could be any oil but with the Ford logo printed on the can. And then we bought a
new biggest Ford backhoe think its was a 7500 anyways same deal to only use Ford 300
oil another warantee gimmick. Ah the backhoe is a diesel right and the new pickup was
a 360 gas job: not only engine oil it goes for hydraulic oil too of course more money than
going to Napa. Not only Ford practiced this all others did also. sam
 
Last edited:
You must log in or register to reply here.
Back
Top