Oil - Another "why" question

[DarkBlack]

Use a good 5w40 oil to fill in all temps on that chart of yours. Think synthetics have little to no VI additive to do this.

You want the low 1st # to get oil to the top end on startups. That's when most wear occurs. A 15w oil will take a second or so longer to get up there, vs. a 5w or 0w oil.

Ralph

I think you'll find the time is the same. I think you'll find the difference is in the drain pattern.

 

[RalphVa]

I completely agree with namesray. Our VW TDIs come with 5w30 and only this is authorized, but others can be used as long as they're low ash and rated ESP (exhaust system protection), but they're all 5w30. There may be some 0w30 versions available for Canada. I'm not sure. VW has never had an oil issue engine failure using this oil and 10k change intervals. They drive these diesel cars through all kinds of climates. I'm sure those engines and engine compartments get much hotter than the more open engines on tractors, and 30w operating temperature oil is all that's needed for them.

I personally use 0w20 oil in my Tacoma rated for 5w30 oil. The filler cap says only to use 5w30. I use the 0w20 because it gives me 1 to 2 more mpg. It mainly gets the oil to the upper parts of the engine quicker on a cold start than any 5w30 would. That's when most wear occurs. I'm now changing it about every 3 years with 6 to 9k miles on the oil.

I use 5w40 oil in my tractor and have some for the first 50 hour generator oil change whenever it gets to that point. Right now, the generator oil is still nice and clear with maybe around 40 hours on it. It's Mobil 1 5w40, and I buy it simply because I cannot find a 0w30 diesel oil for them. If I could, it'd deem it acceptable and buy it. I've also use Shell's T6 in my tractor, simply because it was more available and they don't seem to want to produce a xw30 oil for the diesels, at least to the auto supply stores and Walmart, etc.

I worked in the oil industry for 31 years. I wasn't directly involved with the specific end products. I dealt with making the base oil, but I learned about all the product issues through our research department. They found out that synthetic oil was the best. They set out to develop a way to produce it. We finally did but Exxon decided to merge with Mobil. They automatically got Mobil 1 by doing this. Through research they found out that that 0wxx stuff is far more important than any other xwxx stuff.

Ralph

 

[Gary Fowler]

The problem with the analogy (for the purposes of the oil discussion here), is that an engine operates at a controlled sustained temperature range whether the outside temp is -40F or 110F. True, the body will cool via perspiration, but that eventually runs out without replenishment and is not as effective in high humidity. Engine cooling is a totally different concept. And on HD working engines, gas or diesel, the oil is kept at approximately the same temp as the coolant flowing thru the motor. Whether my Detroit Diesel has a 40w or a 30w oil in it, whether I am hauling something in MN in the dead of winter or in TN in the heat of summer, the temp of the oil is staying within a few degrees of the coolant temperature which is controlled by thermostat. Even the oil cooler has a thermostat. And since one of oil's primary tasks within an engine is cooling, generally a lighter viscosity oil will shed heat via the cooler a little better than a higher viscosity oil. So, the idea of the thicker viscosity for hot weather is negated.

The analogy might correspond better to a air cooled engine.

It works for any engine. Don't tell me you have never had your car engine overheat because it is either working too hard or setting at an idle too long. Your coolant whether air or water has a limit as to how much it can cool. At hotter temps your thermostat would be wide open and your radiator cooling as much as it can but if the temps get really hot (as in a desert with 120F or hotter) the engine temp is going to go up from what it normally runs when it is 40F outside.

 

[buickanddeere]

The same as namesray stated about the highway department, my father has used bulk 15w40 on the farm from the cheapest wholeseller he could find since 1974. 15w40 was used in every tractor, truck, utility vehicle on the farm, never experienced a problem. I used 5w40 in all my equipment and will in my truck when the warranty ends. Bottom line, use whatever oil that makes you feel good but keep oil in it and change it on a reasonable basis.

I don't know why everybody gets hung up on the viscosity and the name brand. Yet ask them what is actually important, the API rating and their response is puzzled looks.

 

[Beltzington]

I don't know why everybody gets hung up on the viscosity and the name brand. Yet ask them what is actually important, the API rating they the response is puzzled looks.

Because the original question has why use 40 weight viscosity rating over 30 weight at engine operating temps. Specifying "high quality oil" assumed the service classification was met, but maybe I should have specified. What I don't understand is how there can still be so many interpretations concerning a product we have been using for decades. Appreciate the comments.