Mom wasn't too bad about oil changes as that seems to have been done once a year and there was usually one long trip a year but other things did not get proper service as far as I could tell the coolant was not changed or at least there was no record of it. When I went to drain it the drain was clogged and I had to open it up with a piece of wire. It now runs free and the coolant has been replaced a couple fo times in the last 3 years. Also the brakes had not been bled as far as I can tell from the records but the master cylinder failed and the whole system has been bled. Also the AC had never been serviced as far as I could tell until this year. To be sure AC is really not necessary in Eastern Washington State but it sure is on a cross continental run in the summer. Anyway I really appreciate this GM Forum and the information available here. This Buick is the first American car I have had since 1981 and it has been interesting to see the design differences that American and European makers employ. Some better some worse. I am amazed how well the Buick does for gas mileage. As a cross-continental car it is hard to beat. Mileage and comfort.

Dead right. With a couple of tweaks, maintenance up to snuff, and 2.84 FDR (tall gears) many have reported plenty of instances averaging 75+mph at 40+ mpg.

Running the A/C will bring that number down admittedly, but it'* not a deal breaker by any means...

Good point! and this is a bit off topic, but has made me think that diesel engines get the credit for their longevity due to their structural ruggedness and the oily natural of the fuel itself, but I'm sure a lot of it is due to how they are run, hours on end in commercial, OTR, and farm applications.

2004 Bonne SLE
1971 Chevelle SS

I would be interested to know what tweaks Rjolly would advise for this engine. I have not seen any mileage like 40 mpg at 75 mph. What I have seen is 28-33 mpg at 70 mph with AC usually running. There seems to be a sweet spot at 68-72 where it runs really well. I have a lot of data as this car has been doing a lot of runs from Boston to Eastern Washington in the last 3 years plus one circumnavigation of the US last spring. Going West the mileage is generally less due to prevailing winds and going east it is generally more. Going faster than 72 and it will happily do it but it does not feel like it is running quite so well and the mileage goes to about 25-30. So I generally put the cruise control at 70. Usually not a problem with the police at that speed. The body has a really good shape and lots of thought must have gone into that shape.

Most power adders will help at cruise. The big ones are Cold air/Fenderwell intake and high flow catalytic converter. Also porting and polishing goes a long ways, including intake runners, touching up the heads, and some work on the exhaust manifolds as well.

But, do them because you want power, not fuel mileage. I have done a couple odds and ends on mine, and have trouble breaking 20mpg on average, with about half my commute on the highway. I haven't been able to figure out why, but i suspect my heavy foot doesn't help any. That is the down side to modding, it helps it suck fuel that much quicker if you want it to. 2 edge sword really, half the time it helps, half the time it hurts.

Interesting! On the subject of cold air intakes: Usually there is a high pressure point at the base of the windshield when the car is at speed. An air intake there would kind of be a poor man'* supercharger and certainly reduce pumping losses through the intake circuit. Lowering restriction on the the exhaust in any way is helpful but mostly expensive. Other ways lowering drag on the body is another way as is tire resistance. Have you ever visited the ecomodder.com site? You might find that useful and thought provoking.

I was also wondering if there was a neat way to upgrade the engine controls to 1997 which would get me to a full OBll configuration which a 1994 Le Sabre is not and also I believe about 2 miles per gallon and 30 hp. Maybe there are some aftermarket PROMs that do the trick as well.

One question that I am having some difficulty with is the pipe from the heater core into the timing case. This pipe seals with an O-ring and a tapered bore with an extra cavity to seal the O-ring. How the #$@%^$# do you get that pipe in place? Is it just a question of strength and lubricant or is there some trick involved?

Posts like Ricer R? I hope that is complimentary as I do not know this person.

Thanks to all on this site. I have found it to be helpful and look forward to making some small contributions when I can.

Well I have put 300 miles on the timing chain replacement and this is what has happened. Went on a longish drive (260 miles round trip) to Connecticut for Thanksgiving and there is no question the engine is running better but I still have the SEL light on. We now have had a bunch of really cold starts and cold starting is much improved. I will have to work on the SEL light. The code is P0342 which is the cam position sensor. Maybe I didn't get it plugged in correctly or something. Good news is that it is definitely running and starting better. Mileage seems better too but I will need more tanks of gas to tell if the mileage is better so it will have to leave it at that for now.