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GM 3800 series I vs II real world mpg

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Old 05-29-2012, 08:59 AM
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Originally Posted by jwfirebird
i think matching the ratio to what type of driving you do will help quite a bit for max mileage. dont think you mentioned what type of driving you want to do?
That actually makes a lot of sense.
Old 05-29-2012, 09:54 AM
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Yes..what I'm saying is how one drives has a lot to do with the transmission surviving.

I've had/known many 3800 cars with original engine and transmissions well into the 180K-200K mile mark.

My current Regal GS got it'* trans replaced by me at 186K miles when a bad coil pack exhibited transmission like issues. I figured at 186K, the behavior seemed like, smelled like and looked like a trans issue. The coil was only found by swapping parts based on not finding anything wrong via scans and knowing the new trans was..well newly built by me.
Old 09-19-2012, 07:38 AM
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I had an 92 olds 88 royal LS and got 26mpg
A 98 olds 88 LS it got about 22 (lower geared then the 92)
A 98 Buick Lesabre limited got about 25
And finally 2004 Buick lesaber limited and it gets around 20

In all honesty the series I engines in my opinion was more consistent. The series II engine is supposed to be more powerfull & fuel efficient.. It simply isn't. They are both fantastic engines but the series II is no better then the I. And the series I seamed a little smoother and quieter especially in Cold weather.
Old 09-19-2012, 08:31 AM
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If you looking at a 95 lss (v nice btw) just make sure to get a good look at the subframe mounts (behind the front wheels) they have a tendency to rust out and cause catastrophic failer.

I've seen manny go on the 90'* models. The upper intake I only had to do once and it was not that bad a job at all. And I had to bypassed the pass lock system on all of then except the 04. But that'* easy to do, takes about 30 min and $5.00 in parts available at radio shack.

None on thease cars were ever towed or left me stranded do to mechanicle failer.
Old 09-19-2012, 10:21 AM
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I have a fairly "new" Series 2 in my Bonne, just cracked 100k on it last weekend actually.

This thing gets 17 or 18 around town, and 27 on the highway if we're lucky. Normal on the highway is 25.5. We net an average of 22 combined.

Of course mine is SC'd with a cold air intake.
Old 09-19-2012, 12:26 PM
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97 SSEI and about 130K, original engine/tranny. Got 31mpg, flat highway driving.

My 94 LSS now has 193K on the odometer. I'm a very easy driver, relatively speaking, but this car was run about 600 miles a week in the states for two years, then spent four years in Russia (on their horrible roads, and I might add, sat for extended periods. I only put 3,000 miles on it in that four years), and going on two years in Bucharest in horrible driving conditions. (Slamming brakes CONSTANTLY, idling for 10 minutes at a time at lights, gas/brake, gas/brake, etc. Never ends. Like playing whack-a-mole with the idiots around here. I've gotten a high of 32mpg on the highway, and a low of 21mpg city, but averaging around 27 city/highway.

I love this car (my only ride here, so I MUST take care of it); the wife hates it, but I'm keeping it until it'* truly beyond any salvage.
Old 09-22-2012, 11:42 PM
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The average on mom'* 2006 Lucerne with the Series III 3800 is around 27mpg. On the highway it gets low to mid 30'*. Not sure of the FDR off hand but I know at 75mph it'* still under 2000RPM.
Old 03-12-2013, 02:37 PM
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Series 1 L67 here. I get 26 mpg in summer, mixed driving but never in big traffic. Exclusive highway upto 75 mpg will give about 29 mpg.

These numbers don't apply in winter.

Also, may seem weird but I got around 29 mpg driving 90-95 mpg in 3rd gear with no hard accelerations but mountain configuration.
Old 03-12-2013, 04:20 PM
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I am also lucky enough to have both Series I and Series II engines at my disposal... Series I in an '87 Buick LeSabre, Series II in a '99 Olds Intrigue. Quite different curb weight, and certainly different transmissions.

My LeSabre won't spin tire unless the wheel is turned, as one would expect with FWD cars. The car is heavy enough that the front wheels stay well-planted. The Intrigue *will* spin tire every single time without even trying (the EBTCM has been bad for quite a while, but I'm not a huge fan of computer-controlled driving, and considering my mother'* driving experience is pre-ABS and pre-Traction Control, it responds in a way that she is more familiar with).

My '87 LeSabre averaged 28.99 mpg with primarily highway driving, in OD, A/C off and one window cracked to enjoy a cancer stick. Considering the weight of the car, and being a good-sized V6, I figure that is excellent. (I had a '94 Cavalier 2.2L stick that topped out at 32 mpg.) The engine is torquey, and I constantly pull away from traffic at a light without even pushing it (it'* amazing sometimes how impressive the pickup is, if you moderate the throttle and balance it with shift points). Unless I'm cruising secondary roads at 50+, or on the highway, I don't use OD. Around-town driving, I average 12-17, sometimes as high as 19 mpg.

Sidenote: my father used to have an '85 *-10 Blazer 4x4 2.8L carb. that ate trannies because he drove in OD all the time and it constantly shifted in/out of OD.

The '99 Intrigue, with the electronic transmission, at 196,500 miles, still shifts as smoothly as it did when I bought it at 27,000 miles. Unless you're accelerating hard, you only know your shift points by watching the tach. Because of the above sidenote, this car is primarily driven in "3." (No OD lockout) At 45 mph, in OD, the engine is turning 1,100 and is really below power curve (can't even spin the AC compressor enough to make it cold in the summer) so in "3" she turns at about 1,350. Combined "granny" driving between my mother and I, mostly secondary/side roads, we get 19-21 mpg.

The Intrigue, I once was driving to Tuxedo Junction, NY, running A/C on highway between 80-85 mph (cruise control, following a California driver) and I averaged 33 mpg. The Intrigue is a very aerodynamic car, and the electronic transmission is geared so incredibly low that top gear is incredibly efficient. For instance, at 112 mph (the speed cutoff) the engine is only turning 2,750 - and there is still 1/3 to 1/2 throttle left.

All of the mpg listed above is running 87 Octane ethanol-blended crap which is mandated in CT. Your Mileage May Vary.
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