Oil selection (10/2009)

[Gunner]

I know, OMG, not another oil thread... but after reading a good selection of the previous threads, the last of which was around April this year, I thought I'd throw out some questions and comments.

707 has 5,700 miles on it and according to the prior owner, is due for a change about now (once a year, just before winter hibernation - although there will be less of this hibernation stuff here on the sunny end of the country). He's been running Castrol GTX 10W-40, which appears to have been a good choice until recent reduction of ZDDP.

So for a well-broken-in FE, relatively mild build with hydraulic flats, mostly street driving but in temps from mid-50s part of the year, 100+ part of the year, and maybe 65-80 about half the year... I get the impression that oil selection is not too critical. I want high zinc, good detergent levels and protection from the time I start it at 50 degrees until I run it street-hard at 105. It's got a Canton pan, remote oil filter and cooler, so I'd guess capacity at around 9 quarts. Slow to warm up, but I will be adding a Canton thermostat to even out the temps.

Joe Lapine recommended Honda motorcycle oil, 10W-40. The most articulate voice in the recent oil threads seems to be patrickt, who was running a funky blend in April because Brad Penn didn't have a 10W-40. They do now. The only comment I have is that both these gents live in a cooler climate, and I couldn't find any definitive posts from anyone in the Southwest arc.

Climate here tends to be warm to hot much of the driveable year, and I can say that driving in temps below 50 would be very rare - am I better off with a 20W-50 than a 10W-40? (Side note: I've always avoided 10-40's because I read a very solid technical article a number of years ago claiming that this was the hardest viscosity spread to create and prone to early breakdown - comments?)

So, knowing that any of these is probably a good a choice as any other, comments on:

• Honda GN4 10W-40
• Brad Penn 10W-40
• Brad Penn 20W-50
• Joe Gibbs 15W-50 Hot Rod Oil

?