Oil Change #4

Had another oil change yesterday.  

I asked Richard if his mechanic could put 20/50 grade oil in my 2000 Accord, LX.  He said "Ooh, that could overheat the engine." Never heard that before. Whenever I put 20/50 grade in my engine, the car always runs better.  Always.  Never noticed a rise in temperature or felt that it was overheating or saw any other visible signs of overheating, so I do not know what Richard is talking about.  

On grades of oil, this was suggested:

Well, he could be right.  As an engine gets more miles on it the tolerances open up a bit from wear.  Thicker oil may help fill those clearances a little better.  It certainly won't do any harm so I would do it.  Another benefit would be that thicker oil would have a harder time getting past the rings, so it would not burn as much oil as it would with a thinner oil.  

Then this: 

There will always be huge debates on what oil is best, so take the following with a grain of salt.  

10/40 is "thicker" than 5/30.  The idea is that since your engine is older, the tolerances between internal components have increased (due to wear).  So a slightly "thicker" oil will do a better job lubricating the engine.  

In reality, the only time it makes a difference is at the extreme temperatures.

But I notice a qualitative difference in how my car runs when I run it with a 20/50 oil, say, versus a 10/30.  With a 10/30, the parts of the engine cycle through very rapid.  

So get my oil changed.  His mechanic put in 10/30.  10/30 seems like a little thin for an older engine.  And sure enough the engine ran thin, did not accelerate responsively and generally ran quite fragile all the while eating up my fuel--a half a tank's worth.  So I drive to my errands and appointments all day yesterday.  I drove close to a hundred miles after I filled up my fuel tank.  Anytime I add oil to my engine, my gas mileage is immediately improved.  Immediately.  It also runs smoother and quieter.  It is amazing what adequate amounts of oil can do for an engine.  But yesterday after driving around and then home, I noticed that I was getting terrible mileage. I used up almost half a TANK of gas after driving only a hundred miles.  My tank holds 17.1 gallons.  So I don't know what is happening.  I will check in on a forum.  I am beginning to lose confidence in Richard.  Maybe it's time.