What type of oil to use

Do you have to flush the engine before changing to synthetic? If so are you flushing the parifin out.

I have run synthetic oil since I purchased the truck, so I am curious about the flush thing

Not to offend anyone, but I don't really beleive the whole peraffin thing. I just think that there is probably some gunk built up inside the engine, whether it be from oil or carbon, tha needs to be cleaned out after 80,000 miles of use. I am thinking of switching to synthetic or a synthetic blend for increased protection with high miles. I don't know if this is right or not.

Yes this would be the best thing to do is use some kind of syn. Its not really gonna matter what kind of basic oil you use its gonna get build up. they all have waxs in them and its best to use syn. Also most syn bond to your motor to protect 100 times better, but like yo were talking about using a high mile oil, its not worth the money. Id just sped a few dollars more and get a bled or just go all out witfull syn.

Even with the cheapo oils, just change them often to avoid problems...

i went to royal purple on mine. i have it in the trans-diff-engine-and purple ice in the radiater. :taunt: :lol:

By far the best oil is Amsoil. It out performs Mobil 1, royal purple, red line and any other oil on the market. I have done lots of research on this comparing spec sheets and no one comes close to Amsoil. That's what I would use.

If you had ever torn down an engine running paraffin based oils you would know what we were talking about. I have run Castrol GTX in engines for 120,000 miles and torn them down and they are perfectly clean when it comes to any build-up on metal parts. I also have torn down engines running Pennz that the owner was proud that the only oil he ran was Pennz. The engine was so gunked up I had to send it to be vatted just so I could work on it. That nasty wax build-up was everywhere.

same here greg. gunked up so bad...had to clean the heads with a steam cleaner.

Greg, what type of oil do you use?

I run Castrol GTX in everything. The engine with 120k on it had zero wear on the piston walls when I tore it down. All the bearings were almost like new. I can't be more pleased with the performance of Castol oils. I even run conventional Castrol GTX in my LS1 instead of Mobil 1 or any others. It's hard to argue with proven performance. I tried Mobil 1 in my Astro for 3 straight oil changes for a total of 12,000 miles and it made zero changes in fuel mileage. I have since gone back to Castrol GTX 5w30 and it hasn't hurt a thing and the fuel mileage is still consistant and the Astro has 170k miles on the stock engine and goes strong without oil consumption problems.