Is 15w40 the wrong oil to use in my 1979 ford f-150 with a 351 modified?

 

it is pretty thick but not much thicker than 10w-30

 

It's only too thick when cold. Once up to temp, it's fine.

 

Thats WAY too thick to be running around here in the winter , WAY WAY WAY to thick , you would be ok in the summer time.

We are running 5-40 full synthetic right now , because we gotta have it in the winter, being as cold as it is here (and with you 1 mile up the road i know it's not any warmer there)

 

oh your in canada! 15w-40 would be fine here in texas! it freezes less than 5 days a year here. the high was 80 today

 

Yup... Around here 15W40 at about -30 degrees Celcius, in the heart of January, flows about as fast as molasses...

 

!!!!!! -30* C? !!!! man thats cold!!!

 

Yeah its a little chilly. But I was just wondering this because my grandfather thinks 15w40 the best oil for any engine any time of year.

 

LOL! I used to work in auto parts and older fellows were always dead set in their ways. a man could have a brand new truck and want resistor spark plugs and run regular gas.

 

Bobby , your grandfather also thinks gray primer will fix almost anything...

 

I used to live close to where you are and in winter ran 5W-30 in all my vehicles and never had a starting problem or any other kind of problem.
With 15W-40 on some mornings you WILL have problems getting the engine to turn over. In any case an oil that thick on a cold morning start will suck the juice from the plugs and may cause hard starting. Don't forget, at those cold temps that you lose starting amps from the battery which means less power to turn the starter motor and less power to the hi tension system. The thicker oil just aggrevates this.

 

Yeah I was pretty sure that this wouldnt be the stuff to use in the old rig. And Jayme is it that obvious that he gets quite primer happy?

 

I use 15/40 in everything now,even the bikes, either rotella or delo. But then again it dosent get as cold here. 20 degrees is pretty much the low and thats only here and there. Get some 5/40 Rotella synthetic.

 

I know of a few of your vehicles that are pretty much two tone now... Heck... that old diesel truck looks like a dalmation...

 

What other ones got the primer treatment mike? (not mine btw)