Oil Recommendation for a 1966 Ford F100

[Death_Eagle_571]

Hey guys, I'm new here, and I just bought a 1966 Ford F100 with the 240ci Straight-6 engine, I'm not sure what oil was in it when I bought it, but it was pretty nasty looking. The oil pressure at 2000-2500RPM was around 55 psi. since then I changed the oil and used Shell Rotella-T 15W-40, it has dropped to around 20-25 psi. the Specification for my engine is 35-55 psi @ 2000RPM I was reading that my truck called for Straight 30W oil, but I was under the assumption 15W-40 would work, and the ZDDP additives in this were sufficient to protect the flat tappets in my engine if I understand it right. Anyway, any ideas guys?

 

[Chris142]

No need to worry about the zddp thing in that old straight 6.the 15w40 should work well. Are you using a real gauge or a stock one?

 

[Death_Eagle_571]

Stock one, seems accurate, it just worries me that it would drop that much, even if the P.O. was running straight 30 in it, which I'm not sure.

 

[zrxkawboy]

Might have cleaned out some junk and plugged the sending unit or a passage to it. Try removing the sending unit and screwing in a mechanical gauge temporarily.

 

[Death_Eagle_571]

I didn't think of that, I'll have to check the sending unit, who knows what kind of build up could be in there..

 

[Doog]

Then get some Rotella T5 30w

 

[Death_Eagle_571]

Yeah, all I could find was T1 30W, is that what I should look for?

 

[ShotGun429]

15W-40 will work perfect and give you long life. Trust me!

 

[Death_Eagle_571]

I hope so, Afterall the 240ci and 300ci Straight-6s were some of the best engines Ford ever made imo.

 

[BikeWhisperer]

Are you using a different filter?

There is a possibility that the filter could be causing the issue if you find your sender to be accurate.

I doubt the oil alone is causing low oil pressure.

 

[Death_Eagle_571]

I'm using the Motorcraft FL-1A Filter. It had a Fram Tough Guard on it prior.

 

[19jacobob93]

Originally Posted By: Death_Eagle_571
I'm using the Motorcraft FL-1A Filter. It had a Fram Tough Guard on it prior.

Not much has changed on those I6s! Same filter as mine.
I'd use any decent 15w40 dino/semi with a good dose of zinc, a 15w should be fine in your climate

 

[dave1251]

Any thing off the shelf that meets current API classification will have more ZDDP and anti-wear additives versus a PCMO from 1966.

 

[Dallas69]

Welcome
Any cheap namebrand 30,40,10-30 or 40 wt oil will work fine
If you want to use 15-40 that will be fine also
I would keep using the fl 1-a filter also
These old 6 cyl engine are bulletproof
How many miles?

 

[Death_Eagle_571]

111,000, I don't think its ever been rebuilt.

 

[SilverC6]

Rotella T5 10W-30 syn blend would be a great choice.

But any dino 10W-30, like PYB or Havoline, would work.

 

[KCJeep]

If it was spec'd for SAE 30 I'd use at least an HDEO 10w30, the 15w40 you picked also is a great choice. Don't know what's up with your pressure unless the PO had something crazy thick in it.

 

[Death_Eagle_571]

Yeah, thats what I was thinking, unless the oil was really sludgey and the filter totally clogged. I'm thinking the 15W-40 cleaned out the oil passages, and possibly exposed that the pump is weak.

 

[zray]

Mobil 1 15w-50.

I use it in all of my vintage cars, and it is the oil of choise for any vintage car I work on.

Z

 

[bigt61]

Originally Posted By: zray
Mobil 1 15w-50.

I use it in all of my vintage cars, and it is the oil of choise for any vintage car I work on.

Z

Yeah, your vintage cars are clean & pampered - I'm sure the M1 works great. In this old "possible sludge monster" truck, maybe not so much. The fresh oil might have dislodged enough junk to partially block the pick up screen reducing oil pressure. I'd drive it gentle & easy for a short OCI and see what drains out - chunks are bad. 10W-40 SuperTech is likely all you need in the future.