1997 850 Premium and Lucas Rule

davolvo · Post by **davolvo** » 11 Mar 2014, 08:04

Holy Schmokes! Two weeks ago I put in a small bottle of Lucas Fuel cleaner with mid grade gas. My mileage before was 20 it increased to 22 and then 24. I filled with premium and one more bottle of Lucas and today I drove 60 miles; my fuel gauge barely moved so I topped off and it would only take 2.1 gallons. Really? Is something broken? Now I am getting almost 30 miles to the gallon? Pinch me.

Post by **E Showell** » 11 Mar 2014, 08:52

Might be time to check the functionality of your front O2 sensor, especially if it's been about 100K miles since it was replaced. This is a maintenance item at 100K that a lot of folks overlook. Increased gas mileage can be a sign of lean running. My O2 sensor failure was slow enough and over a protracted enough period that it did not throw a code until the damage was done. Code and burned exhaust valve were the result of the protracted failure.

davolvo · Post by **davolvo** » 11 Mar 2014, 09:21

Well, I can certainly have that checked. Thank you!

Post by **northernlights** » 11 Mar 2014, 11:40

davolvo wrote:Holy Schmokes! Two weeks ago I put in a small bottle of Lucas Fuel cleaner with mid grade gas. My mileage before was 20 it increased to 22 and then 24. I filled with premium and one more bottle of Lucas and today I drove 60 miles; my fuel gauge barely moved so I topped off and it would only take 2.1 gallons. Really? Is something broken? Now I am getting almost 30 miles to the gallon? Pinch me.

Keep in mind the original bogus EPA ratings for that car was 20/29. It is bogus for two reasons:

1) The testing employed was the FTP-75, which was their state-of-the-art test proceedure....in 1975!
2) Because FTP-75 was found to be not very realistic, they eventually reduced the numbers they calculated during testing by 10% city and 22% highway.

This means that per the original EPA test, your Volvo 850 achieved (29)/(0.78) mpg, or 37 mpg. Of course, top speed for this test was 60 mph. But, if you are not driving too fast, cruising steady, and not running the AC, you may do better than you expect.

Note a curious effect of the calculation method. If one's 6000 SUX gets 12.8 mpg in the test, they report 10 mpg as the 'corrected' number. On the other hand, a 50 mpg test result for the Bantam Blaster comes back as 39 mpg. Makes the lumbering monsters look less bad in a special kind of way.

nnn4865 · Post by **nnn4865** » 11 Mar 2014, 13:41

i recently bought a 97 850 wagon, base model with manual 5speed. picked it up in los angeles and drove it back to denver, co and got 30mpg the entire trip with regular. since then in town has been averaging a little above 20mpg.

Post by **QuirkySwede** » 11 Mar 2014, 15:13

http://www.lucasoil.com/images/medialib ... 99C5F8.pdf

"I'm addicted to placebos... I'd quit but it wouldn't matter." -- Steven Wright

davolvo · Post by **davolvo** » 11 Mar 2014, 15:39

Your link did not work QuirkySwede

What were you trying to show us?

difflock54 · Post by **difflock54** » 11 Mar 2014, 15:58

Worked okay for me davolvo. Have you got a pdf reader program installed in your computer?

Post by **rspi** » 11 Mar 2014, 20:02

Whenever you add Lucas or any other fuel tank additive, you should run the tank down as far as you can before you add more gas so the cleaner, additive will have the process to do it's job.

Post by **scot850** » 11 Mar 2014, 20:18

Was your driving city or highway? A few years ago, my folks visited and borrowed or 93 850 N/A auto. When we calculated their mpg on the return it was just under 34 mpg (US gallon) on a 700km trip. Most of the driving was on highways and back-roads. Years ago, a friend in the UK had a stick shift 740 NA and he regularly managed 32mpg (US gallon).

If you are mainly city driving, I would be concerned of lean running.

You may be worrying unnecessarily!

Neil.