I know I need to use the 10w40 oil in my 289 but I have been told not to use the syenthic oil as my engine has never been rebuilt and has 100K on it and I should just stick with a good regular oil. Is this true? Also in stores i saw a product called engine restore it is supposed to be added to the oil at a change and help return performance. Has anyone ever used it?

Thanks

 

as far as synthetic goes i wouldn't because for a 66 with 100k miles on it its nearing the end of its life any way. i think it would just be a wast of money when, you do get a rebiuld go ahead and run synthetic after the break in this is where the synthetic will help the life of the motor.

when it comes to oil adatives i don't but a lot of poeple swear buy them i kinda think its another waste of money.

 

I agree Restore type products are really just a band aid type fix. Also your fine using regular oil and changing it every 3000 miles.

 

should differnt oils be used in differnt weather, like winter time when its cold vs. Sumer time?

 

Only if the temperature gets really low, like below 0* a lot. Especially with an older engine like that, where the bearing clearances are probably a lot more than they used to be, it shouldn't matter that much.

 

Here's a good link to an oil site with every conceivable answer.http://www.bobistheoilguy.com/

 

you shouldn't use synthetic oil in a high mileage motor unless it has had synthetic in it its whole "life". the synthetic oil is actually too slippery and it can allow parts to move more than they should since the tolerences in the motor aren't exactly what they should be. regular oil has also builds up deposits over time and the synthetic oil will find its way past seals more easily. my gf's dd del sol (has a 05gt too) actually specifically says not to use synthetic oil in the owners manual. as far as the oil restore (if it looks like an old silver can)....i used to have a 12sec awd turbo talon as my dd that had the notorious (for dsm's) lifter tick. the tick would trip my knock sensor which lead to a whole list of performance problems you don't need to know about. anyhoo that engine oil restore stuff was the only thing that ever worked to stop the tick w/out replacing the lifters plus it raised my oil pressure about 5psi at idle...so it "works" to a point, but as jd said it's just a band aid