Ordered the HPL Performance Oil in 5W20 (recommended in owners manual) 6 qts and 1 qt of Engine Oil Cleaner 30. Also *splurged* and ordered the Amsoil EA series full synthetic filter. Is it overkill? Of course. But it's an experiment I'm curious to run.
I own 4 Honda Odysseys with the J series 3.5L V-6 with VCM enabled.
I used to use 5W-20 as recommended in the owners manual.
But I permanently switched to 5W-30, as some ASE auto mechanics on BITOG who repaired these engines for sludge accumulation commented that they thought 5W-20 oil was too easily causing varnish on the front 3 cylinder heads.
Also, 5W-20 oil has a HTHS of 2.6, which is right on the boarder line of adequate wear protection.
During an oil change interval, the oil will shear below 2.6, which the following chart shows puts you at risk for higher engine wear.
If you google this: HTHS wear graph
you'll see lower engine wear with a higher HTHS oil (like 5W-30) at 2.9+ (Most thicker 5W-30's are HTHS 3.1 to 3.2, with some euro 5W-30's at HTHS of 3.5+).
Also, dirty oil causes varnish, sludge, carbon buildup, and gums up the oil control ring/piston ring area.
Dirty oil doesn't show up on oil analysis, so someone could submit an oil sample to an oil testing lab with 10k miles on it,
with the oil in the drain basin flowing murky, sludgy, dirty as can be, and the oil testing lab could come back with a good report.
But to me, I prefer to only leave the full synthetic oil in my engine for 4k miles maximum.
Oil is so cheap, I'll never understand the need to leave it in the engine for 5k or 7.5k or 10k miles.