Classic/Antique Car Repair: 66 Mustang Oil Change, variable viscosity, engine coolant temperature

Question
Hi Dick, I'm a new proud owner of a 66 Mustang coupe - 289 v8.  I want to do my own oil change and wondered if you will kindly tell me which type of oil I should use in the ole gal.  I've heard to stay away from synthetic products when changing all kinds of fluids on classic mustangs.  What are my options?  Thanks a bunch, Robin :)

Answer
Well, my goodness - something went wrong here.  This question dates from before I left on vacation on 9/22 - and should not have been allowed by the system, or it should have been directed to another volunteer.  Since I find it in my in-box, I guess you are still waiting for an answer?   I'm sorry about that!

Anyway, I prefer straight premium grade traditional oil - I use NAPA stores premium brand SAE30W oil in all my old cars - I do not use the more modern variable viscosity oils such as 10W30 in any engine built before about 1980 - as it is much too thin for our old engines, in my opinion.   The thinner oils are really for current production engines, which were designed to tolerate them and produce maximum fuel mileage on them.  The synthetic oils are much too expensive for my pocket book, and tend to be too thin also.   My answer was based on where I live (Southern California).  Thinner oils like SAE20W are needed if you live in the frozen north, where temps below 32F are common.  Thicker oils like SAE40W are hard to find, but if you live in a VERY hot area and drive hard miles at high speeds, you should search for it or even SAE50W, especially if your engine is somewhat worn out.  

The main thing to watch for is the API specification on the oil - use rating SL or SM oils and your engine will last a long, long time.  The more important issue is how often you change the oil - at least every 3000 miles, and change the filter with every oil change.  The 289 will go 200K miles without problems if it is well cared for.  Also, make sure the engine coolant temperature is staying between 190 and 210 during normal operation - if it is running too cool or too hot, it shortens the life of all components and the oil.

I hope this isn't too late to help!

Dick