5W/20 in older engines???

[otis24]

I have a 1983 Ford F150 with 83K actual miles. It runs great! I am currently running Havoline 10w30. I am also in the process of running Auto-Rx (cleaning phase) through the engine.
Can I run 5w20 Havoline in this pickup? Will I see the fuel economy improvements supposedly inherent in the 5w20? Are there any disadvantages to running the 5w20? Can I run it year round or should I just run it in the winter? (I live in South Dakota). Please share your input!

 

[AEHaas]

In the 1970's and 1980's many 30 wt. oils rapidly became 20 wt. oils so the car may have been run on 20 wt. oil for years. With 83k on the clock you have to figure out if the engine is worn. If not, then I would run a 20 wt oil in there year round.

If there is wear however, you may need a true 30 wt. oil now. With additional wear engines will need thicker oils, but when is a matter of testing.

aehaas

 

[TallPaul]

It would be nice to find out what the oil pressure is with the 30 weight you are now running.

I would be inclined to run Redline if I were running 5w20, expecially in a vehicle not back specified for it.

 

[Gary Allan]

The fuel economy that you're looking for will probably be mainly apparent if you're doing short trips (around 10 miles or less - maybe 13-15). That's when parasitic losses are the highest. You can also feel confident that you're oil isn't at its true spec visc until beyond that time too.

Perhaps if you describe your usage, it will be a little easier to figure out.

 

[otis24]

I generally make pretty short trips, 2-3 miles. The truck sits a lot.

 

[simple_gifts]

Odd you posted this question. I am on my 2nd ARX on a 1989 F150 I6 (175,000 mi) and was wondering the same thing. As TallPaul suggested, Red Line 5W-20 seems like a good choice; but in the light of my occasional usage (and yours) it is probably not worth the money. We're talking SIX quarts.

 

[Gary Allan]

In 2 or 3 miles ..the oil barely warms at all. It may gain 20 degrees over ambient ..if that. In the middle of your winter ..it won't even qualify as a 40 weight (no, I didn't really punch the numbers into the visc calculator - I pulled them out of some dark place ..this is a swag

)