Couple questions about my new 86 460
 

I have recently purchased a 1986 f250 with the carborated 460. I have a few questions that may seem stupid so I apologize in advance. I'm new here so don't be to hard on me haha.

So the odometer reads just over 5,500 miles. PO says it only rolled over once so that's 105,500 miles. I do not believe him so im going to say it has 205,500 miles. How much life can I expect out of this engine assuming its had better than piss por maintenance but not great.

What oil should I be running, assuming the engine is all stock.I've been reading on here and it seems like the"modern" oils are not good for these engines? And I've read about people running diesel oil or additives.
Please enlighten me on this as the threads I've looked at get confusing.

And this isn't an important question but would a drop in k&n air filter have any benefits over the paper ones on this old thing?

Those are my questions so far
Thank you for your time,
Spencer

Probably little or no improvement with the K&N filter. Won't hurt though, and the fact that you can wash & reuse might help justify the price.

205,000 miles, if indeed it has that many, is a LOT for these engines. They're reliable and tough as nails, but being carbureted limits the number of miles you can reliably get out of one. The mixtures on a carb are nowhere near as precise as EFI, so you end up with carbon deposits, extra fuel in the oil, etc. As the engines age and components/seals wear out, the problem worsens.

That's not to say EFI is the holy grail, but it's not uncommon for EFI engines with routine maintenance to make it 200-300k miles before they're truly worn out. In the days of carb'd engines, 150k was considered a long, healthy life. Only a compression / leak down test will give you a clear picture just what condition the engine is in, especially not knowing exactly how many miles you've got on the rig. It's way too easy to swap clusters in these trucks, so for something 27 years old, you have no idea what the real mileage might be.

My '85 was also advertised to have not rolled over, putting the mileage around 98k. A VIN check was inconclusive, as the last reported mileage was 80-something thousand in 2002. Hard to believe it had only racked up 10-15k in 10 years, but who knows. You might try a VIN check on yours to see what mileage has been recorded where.

For the oil, I would recommend diesel rated (API CJ) 10w-30 (all climates) or 15w-40 in a warmer climate. The flat tappet camshafts in these motors like a lot of ZDDP which is an anti-wear additive whose use is limited in passenger car motor oils. Anything beyond API SL has a cap on the amount of phosphorus (a component of ZDDP) in the oil. Diesel spec'd oils do not have this limitation. There are a handful of high-mileage oils that have extra ZDDP; Quaker State "Defy" is one of these, and is a fine oil for this application.