I apparently don't understand oil weights

Username Taken · Mar 18, 2021

RalphVa said:
That makes sense. <snip>

But it is completely wrong

RalphVa · Mar 18, 2021

Well, the upper outside temps on the charts do not make sense otherwise, unless they're for air cooled engines. All oils in water cooled engines run at around 212-230 F, being cooled by coolant at 190 F thermostat setting. VW TDIs, millions of them, run around with 5w30 in their crankcases. None have ever had an engine failure due to oil, according to VW.

Sberry · Mar 22, 2021

How would the oil know how warm it is outside once its running?

Sberry · Mar 22, 2021

If 5W30 is supposedly only good below 50F, why are they spec'ing it for all temperature ranges?
It isnt "only" good there,,,, they just reccomend the 5 for lower temps.

Sberry · Mar 22, 2021

Bout like 110 and 220 volts.

Sberry · Mar 22, 2021

Gotta love the guys on Bob,,,fussing over their 5K changes endlessly and telling everyone how they should really sample to get at the truth,,,, then a guy pulls it at 41K and its still 50% and he is going to hell for sure. More living proof we can "research" more and know less.
I have seen a lot, a lot of stuff stops equipment, wears it out over long times. Its really people more than machines. Changing the engine oil can be a good thing but its not the only thing. Rear lube and keeping the vent open pays off, doesnt have to be like a bat out of hell but a freshen with new fluid about 1/2 way thru doesnt hurt. I know people obsess about having an oil change,,, break out in a sweat at 3500 miles but can somehow drive a car till the fins on a rotor are thru and blows out a caliper,,,, but,,,, I cant understand it,,, I have the oil changed all the time. Try splainin how they noit directly related and skipping a change wont hurt but wearing the pads thru just cost 500$,,, but get those deer in the headlights look,,, well I wouldnt want to have to replace the engine so I change the oil every 3K and simply dont see how the wheel fell off,,,, after all I change the oil regular,,, I am a firm believer in that.
19.95 oil special and all of a sudden an expert in car maintenance.

Username Taken · Mar 22, 2021

Sberry said:
How would the oil know how warm it is outside once its running?

Most engine wear (about 90%) happens at cold starts.

Once an engine is running it depends on how it's being used. Severe duty can break oil down. Heat breaks oil down.

In a diesel, as longs it's in good shape, run 5w-40 synthetic and just drive it.

LouNY · Mar 22, 2021

^^^^^^ Too simple

RalphVa · Mar 22, 2021

Username Taken said:
Most engine wear (about 90%) happens at cold starts.

Once an engine is running it depends on how it's being used. Severe duty can break oil down. Heat breaks oil down.

In a diesel, as longs it's in good shape, run 5w-40 synthetic and just drive it.

Exactly. That's why it's very important to get a small "x" # in a xw30 or xw40. A tad fuel credit for xw30 vs. xw40, but it's on the order of 1-2%. Main thing is to get a small first # which allows the oil pump to "grab" the oil instantaneously vs. sitting there "warming" the oil by not pumping it for a few seconds, with your bearings and upper valve train starving for pressure lubrication.

A synthetic will stand severe duty and heat a lot better because it has a higher boiling point for a given grade of oil.