Nolan

I have had my truck for a year and a half and have used Valvoline motor oil mainly because the old owner used Valvoline. A friend of mine got rid of his truck and has a case of regular Castrol GTX in the same weight as what I use that I can have. Is there any problems which changing brands or should I just stay with what I have been using?

FirstToy

Here's an article on Irv Gordon- he put 2 million miles on his P1800 (80 laps around the earth). More than 35 years after Gordon took the keys, the car has the same engine, same radio, same axles, same transmission, and of course, the same driver. He is the only person who has ever driven his P1800.

There is a top 10 list to make your car last. One of them is to stick to the same oil.

http://www.canadiandriver.com/news/020312-5.htm

Highland Runner

It shouldn't matter a bit as long as you use a good quality/brand. Don't buy oil from the dollar store. From what I've heard is motor oil baestock is made by only a few companies. That is bought by Castrol etc. and additives are put in. That is the important thing. check out http://theoildrop.server101.com/cgi/ultimatebb.cgi? . It is an excellent site covering oil, filters, etc. A good filter is very important also. I use a Purolator Pure One, and NEVER use a Fram.