Hello,
I just picked up a 1990 F250 with 55k miles. Any reason not to use synthetic oil in the 460?

Thanks!

 

My 460 has a main rear seal leak which loses less than 1/2 a quart of oil per month on regular motor oil. I tried synthetic at the same weight and it started leaking about 1 1/2 quarts per month so I switched back.

So if your truck leaks any oil from anywhere, it will probably get worse with synthetic. If your's doesn't have any leaks then it certainly won't hurt.

 

Hi,
No reason what so ever, and....

Your motor will thank you!

 

As was mentioned already, if you have leaks they will leak worse. High mileage full synthetic is a good way to keep leaking down if you have current seal leaks and want to run full synthetic. Full synthetic is the way to go especially if you live in a colder climate.

 

I've always ran a synthetic blend to get the most out of leaky 300. Valvoline high milage is what I use

 

I have been using Royal purple 10w30 in my 5.0 and I lose nothing at 200k miles.

I have also used Valvolines Maxlife oils, and never had issues with them either.

 

I run that oil in the summer. Mobil 1 high mileage 5w30 is my winter oil. Recently had the valve covers off the engine and there was very minimal soudge(I do a lot of short trip driving and cold temperatures take their toll).

 

Thanks for the input. No leaks (currently) in my motor. Synthetic is going in tomorrow.

 

I am running mobil 1 extended performance in my 351w. I just rebuilt it this fall, and after a hard break in on dino oil I wanted to help the bearings last.The flow at very cold temperatures was a major selling point for me. We've been down around -35F a few times this winter. Cheap oil is crazy thick at that temp. Block heater plus good oil, the truck fires right up. I'll be sending in an oil sample to Blackstone labs shortly, since I've got 5k miles on the oil and want to know what a good change interval is. By far, regular changes matter more than oil type overall, but synthetic does offer better protection at extreme ends of the temperature spectrum.

One thing to consider is that you have a flat tappet cam in that 460, most modern oils lack the ZDDP levels that motor was designed for. Not as big of a deal with the cam broken in but I'd be looking for higher levels than lower. I know some Mobil 1 oils have pretty low content and others are surprisingly high. The info is on their website, might take some digging to find.

 

right on with the block heater and synthetic oil. Starts the same as when it's 70 out. I don't buy into letting synthetic oil go too much longer between changes. The oil still gets diluted by gas. You are right about wanting to avoid some oils if you have the flat tappet cam. Try to find sl rated oil. SN oil has much less zddp.

 

Mobil 1 in the single quart jugs is sl rated, but the 5 quart jug is sn rated. I don't know why, but that's what I have seen for awhile.

 

I've run full synthetic from day 1 (0000008 miles on the odo) on my 96 HD 250 4x4. Never had any motor-related issues-ever. No leaks. Currently has 360k on it and has never been opened. Worst unrelated to oil thing about this engine are my exhaust manifolds-currently on my 4th pair.
On my 2nd truck, 95 250 4x4 which I bought w/120k on it, switched over to full synth when I changed the oil for the 1st time under my ownership. At just under 200k I have no leaks and winter start-ups are easy.
I don't think anyone can come up with a negative for using synth oil.....on the contrary, I'd think there'd be MORE negs using conventional oil when you weigh the 2 against each other.

 

Only negative is making current leaks worse and the price of the oil. Other than that synthetic is better in every way.

 

Synthetic is excellent, I personally used royal purple 5w-20 in my 93 460. Ford back-specced the 460 and most other engines that are 93 or newer to 5w-20 oil. However I am probably gonna move up to 5w-30 or 10w-30 to reduce consumption, blowby, leaks, etc. But one nice thing about royal purple is it still contains a sufficient amount of zinc which is good for our flat tappet cams.