4.0 V6 conventional to synthetic oil change at 150k miles

The concerns about introducing leaks by switching to synthetic are a hold-over from back when cars had much simpler seal designs. Like rope crankshaft seals and cork gaskets.

Those days are long gone

 

I don't understand why they still make conventional oil. No reason to ever use it and it won't hurt to change now.

 

I run it in my diesel f250 7.3 witch takes like 4 gallons of oil conventional is recommended.

 

That engine is 20+ years old. The recommendation for conventional oil is also 20+ years old. It won't hurt a thing to use synthetic in it. 4 gallons is a lot, but while synthetic costs more, it lasts longer and protects better. Overall cost ends up about the same.

One of my wife's brother has a 1999 with about 300,000 miles on that engine. He switched to synthetic years ago.

 

Conventional oil is better if you do a lot of nighttime driving.

 

Not saying it will hurt it to go senthetic just haven’t switched.

 

Would y’all suggest OP runs a couple cycles of valvoline RaP?
I got my truck at 140k, 2 oil changes so far both done by me, full synthetic high mileage.
Previous owner just would get the cheap stuff at jiffy lube. Would I (or OP) be opening a can of worms by running some of that? I wouldn’t mind spending the money maybe do a 500 change (filter and oil) then 1k then 2.5k then back to 5 k. Apparently that stuff frees up a bunch of gunk so oil filters won’t last the whole 5k.
I’m so tempted

 

Opening a can or worms? No.

Wasting money? Probably.

I don't recommended fixing problems that don't yet exist.
If you aren't burning oil, I'd just continues to do regular oil changes.

By all means, Do it if you want.
It's not going to hurt anything. But will it help anything is the question?

FWIW, I have a friend that runs a local service shop.
He has used Valvoline Restore & Protect on a few customers cars.
He said Honda and Subaru seem to be the ones that respond better.

 

So your saying I need a car that is less reliable
I’ll probably do it becaude once I discovered it, and confirmed there is no downsides, I no longer have a reason not to.
Besides I enjoy stuff like that, if it makes my car better and clears a ton out, great! If nothing happens, I can still lie to myself

 

Nothing wrong with that...
I too lie to myself. Mostly to convince myself "I can do that tomorrow"....
I'm a master at procrastination.....

 

That’s exactly what I thought. When my dad said he used conventional, I asked where the F do you find that? At a tractor supply store or you dig it out of the ground or something? Did you buy a 50 gallon drum in 1985 and you’re still using it up?

 

Almost all the 5w-30 I've seen was at least a synthetic blend.
Even the Wal-mart stuff.

Only Conventional I've found was straight weight. Like SAE 30.

Then again, I haven't looked too hard. I'm not an oil snob.
If it looks like oil, feels like oil, and smells like oil. It's oil to me.

 

I’m trying the restore and protect will see if it actually works it’s not anymore expensive than what I was using before so I’m trying it.

 

Conventional still exists to some degree but only in the more true to base stock viscosities. Such as 5W-20, 10W-30, 10W-40, 20W-50, etc. You can switch to synthetic and it will be fine, or you can run conventional and it will also be fine. While synthetic is touted as ‘better’, I have yet to see a single convincing argument that actually proves it does anything to help an engine last longer term. We didn’t have engine problems before synthetic came along that synthetic solved. The wear spot on project farm videos don’t count - those don’t prove anything useful. You can switch all day long, just don’t think it’s going to provide any measurable pros or cons either way.

 

Also, conventional oil doesn't contribute to reverse hysteresis in your MAF sensor.

 

Lol... there are a lot of old pushrod V8's still running around that are better off running conventional vs. synthetic.

 

And it smooths out the pulsations across the coolant temp sensor, resulting in better fuel calculation at startup

 

For the OP's truck, it started life with 3,000 mile oil changes. I wouldn't use any "clean out" additives nor any "high mileage", "stop leak" synthetic oil or anything else. Pick a name brand like Synthetic Mobil1, Castrol, or Valvoline in the recommended viscosity and an OEM oil filter for $5.50 and stop chasing Phantoms with 500/1,000,/2,500 oil and filter changes, additives or STP oil treatment if you can still find it.

 

Who’s gonna stop me
Edit: maybe I’ll do all at once, valvoline RaP, additives and short oil changes