Quote:
Originally Posted by ga traveler
I built engines for Delta Air Lines for 15 years. (prop and Jet) Delta wrote off $50,000.00 from the government for my schooling. taxes. ( I found this in my paperwork when retiring.) I have posted before that I am not picking at people, or finding fault. I just try to keep wrong stories from living forever. It has been fifty years since I went to school on oil. If I remember correctly, Oil weight is determined by putting oil in a container with a hole drilled in the bottom. according to which size hole the oil will pass through, that is the viscosity. 10 wt oil will not go through a 5 wt hole , etc. Straight wt oils are thicker as you go up the scale. So are the multi viscosity oils. Yes many people switched from 10W30 to 20W50. As I said before the first number is the viscosity. Therefore they went from a 10 wt to a 20 wt. with either oil.
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This reminds me of a discussion we had on a night shift.
At a coffee break the topic was oil and of course some of it was based on fact some and I would say most was based on opinion.
Because the temp was minus -40 we decided to put three cans of oil outside for aprox 6 hours.
30wt.......would not pour
10wt.......would pour but not well
10/30wt..poured good and of course nobody new why but it did.
This was in the early 1970's
I was running 100 Aeroshell in my aircraft and in the screen I would get carbon buildup. It was really hard to keep the engine temp up in cold conditions.
I even had the orifice on the oil line plug with carbon which indicated that I lost my oil pressure.
I switched to Aeroshell 15/50 and my carbon problem went away and I was no longer having issues with engine heat.
I am not a techie but I would sure like to here some opinions.
40 years later and 3 aircraft i still us multigrade in everything.
the 460 I use Mobile fully synthetic 5w/30