Castrol GTX or Mobile 1 synthetic in 4.6L

Ok so I am a Castrol person and I am because my dad is, go figure it is passed down, well to get to my question I have a 97 bird with a 4.6 its a very healthy engine with nearly 100,000 miles on it, It is my daily commuter and I drive over 50 miles a day so I change my oil alot because I drive under heavy conditions up and down hills etc. I want to know what your opinion is on this new Mobile 1 oil that you only change every 15,000. All I know is what I have heard and that is once you go synthetic you cant go back.. Please help me I want a good oil that will keep my engine running forever and that i dont have to change every month...

I dunno... I'd personaly never leave anything in my car for nearly that long... Not even if Willy Wonka got into the oil business and named it, never changing gobstopper

I Have to agree I would be leery about leaving oil in my car that long.... that's why I need help I mean I change my oil every 3,000 to 5,000 . just looking for what all you other guys use in your birds.

Personaly I usually use a high mileage blend(valvoline, penzoil, etc...)

I used mobil clean 5000 once.. And i'll tell ya, I let it go a touch over 3000 miles(which I NEVER do..), and it looked as clean as the day I put it in my car... That stuff did impress me...

But still as much as it is a pain in the ass to change so often, i'd never let my car to long without a change... no matter how good the oil looks!

I change my oil every 5000 miles and am using Mobil 1. I used to use GTX in my cars and changed the oil every 3000 miles. There is no reason you can't switch from dino to syn and back again as long as you drain all the oil and change the filter at the same time. Don't mix the two types together. I'll stick to changing the oil every 5000 miles using Mobil 1. I haven't had to buy any lately so I don't know what and if there is a difference in price between the regular Mobil 1 and the 15K type but I'd need to see reliable test results before I went to 15K between oil changes!

So I was told my many other ford people to stay from valvoline, whats your say, also do you think i should switch to a high mileage I mean my dads astro van has 180,000 miles on it and he still puts castrol in it and that van's a 94 it doesnt leak a drop.. More opinions?

synthetic oil developed for army ww2 credited with making tank and aircraft engines last longer and more dependable. does not break down as fast and withstands higher temps. brands of oils to me is a matter of choice, no doubt some difference due to additives but overall little difference. changing oil is a headach and these days and expensive but why change your routine if it has served you well so far. synthetic oil best, blend second, regular third and you can tell it in price, schedule oil change? go by DEALER recomendation not oil maker

i have a 95 4.6 and i use the mobil clean 5000 and i have never had a problem with my oil. i have over 250k on my baby.