HM viscosity and choices

[Silver]

I've got a '96 Ford with the 351 in it, stock. It's had Valvoline and Havoline dino 5w30 most it's life, 83k on it now. It has had for the longest time a very very slow leak from the rear seal. I'm about to change the oil before heading offroading this weekend (lots of slow movement and idling, forecasted 80 deg temps). I'm thinking of going to a dino HM to try and begin to swell the seal if possible. Otherwise, the engine runs like a top and appears very clean under the valve covers. Oil never 'shows' bad at changes but the truck does sit for weeks without being driven.

What I -think- I want is the thinnest HM out there in dino b/c I don't need a thicker oil, as HM's seem to be, but only need the conditioners. So, question #1 - does this logic make sense? If no, how so? If yes, what's the thinnest HM dino?

Any comments welcome.

Thanks,
Mike

 

[TallPaul]

I'd go Maxlife Blend. It's a tad thicker, 11.5 cSt instead of 10.7, but that is minor considering a 10w40 is around 14 cSt.

What is the 351 in? Presumably a pickup, or maybe Bronco. Don't think they came in any cars by '96. Great engine, gobs of torque.

 

[Silver]

Good guess - Bronco

It runs way different than all the older 351's I've driven though. Not as much low-end grunt but smoother, more linear power curve and better top end. Maybe something to do with the OBDII/MAF switch in '96. It's an odd duck

 

[VK56VD]

Try Auto-RX. Some have claimed it stopped minor leaks.

 

[OVERKILL]

It's a roller engine. The older ones you drove were probably flat-tappet.

Rear main isn't too bad to change, is it auto or stick?