1986 Cutlass Supreme MPG and milage improvement

[olds307 and 403]

Your 86 is CCC correct? Make sure all the vacuum hoses are in good shape and no codes. Do a complete tune up with quality parts including the air filter. Add a better flowing muffler like a Dynomax Super Turbo or small dual exhaust if you don't have emissions testing. A 2004R will help big time for highway mileage if you have a 3 SPD. Yes, ethonal kills mileage. With my old 81 Delta 88 non CCC Olds 307 powered with 250C trans and 2.41 gears Mom got 32 mpg imperial on one tank. Otherwise mid high 20's, slowly dropping over the years.

 

[Ericja]

Yeah, about what I expected for mileage. Definitely interested in upping it. I know some old hotrodder tricks can work no problem on anything as recent as a 70s model A body. Any hope for the G body there?

And yeah, why in the world would I want to DD one of these? I know its probably a dumb idea in the long run but its a collection of reasons that make me want to do it. The foremost of which is a wish to drive something I can learn to maintain myself. On top of that, its a comparatively low cost to get into something that I own, not a bank. I also learned to drive on large vehicles. A 1 ton truck to be exact, it was my DD for 2 years. And in my circumstance, a breakdown or issue that I cant fix overnight wont leave me too stranded. Work is less that a KM away and groceries aren't much further. I would also be able to use a car when this one is unavailable.

And yeah, its a safe assumption that its CCC. Having said that, pretty sure this model year is exempt from E-testing.

 

[TURNA]

The factory specs on show a 1-3 mpg increase with the 4 speed trans.

Something to think about before investing into an OD trans.

I think it is worth it and honest thought it would have been a higher MPG difference.

But installing one would all depend on your financial situation.

A good quality built 2004r or 700r4 can get pricey fast.

 

[L67ss]

I'm mainly going od trans to help the engine last longer

 

[pontiacgp]

The factory specs on show a 1-3 mpg increase with the 4 speed trans.

Something to think about before investing into an OD trans.

I think it is worth it and honest thought it would have been a higher MPG difference.

But installing one would all depend on your financial situation.

A good quality built 2004r or 700r4 can get pricey fast.

that would be on average but I think if it were calculated on highway speeds it would be more than 3 mpg increase

 

[UNGN]

Not to mention those MPG numbers were in perfect track conditions and most likely padded a bit.

And the speed limits were only 55 mph.

Subtract 10% from the highway mpg to go 65mph.

 

[ed1948]

Tall skinny tires =almost OD ratio

 

[L67ss]

Tall skinny tires =almost OD ratio

and death of city mpg

 

[TURNA]

And the speed limits were only 55 mph.

Subtract 10% from the highway mpg to go 65mph.

65 ??? whats that???

Here in our loving Socialist state of NY..... We The People....have 50 mph speed limits on our expressway!!!!!

 

[L67ss]

What are speed limits?