Va Maddog Posted August 18, 2005 Report Share Posted August 18, 2005 I have used regular and mid-grade with my 95 SLS and the Northstar with no issues. I was wondering if the same is true for the 4.9L engine from the early 90's? I read a post on another board that had an owner getting 29-32 mph with his 4.9L 93 Deville on the highway. Anyone have similar experiences? I have my eye out for a 92 or 93 DeVille with the Touring Sedan Package (Actually a unique model) Not many clean ones around anymore as they did not sell a lot of them. Anyone here have one or previously own one? How did you like it? Link to comment Share on other sites More sharing options...
adallak Posted August 18, 2005 Report Share Posted August 18, 2005 The short answer is 89 will work just great without any modification and 87 will work too if you set the timing at 6 instead of factory set 10 degrees. The saddest thing in life is wasted talent Link to comment Share on other sites More sharing options...
JasonA Posted August 18, 2005 Report Share Posted August 18, 2005 I read a post on another board that had an owner getting 29-32 mph with his 4.9L 93 Deville on the highway. Anyone have similar experiences? You should be able to easily match that with your '95 SLS, Maddog. Jason(2001 STS, White Diamond) "When you turn your car on...does it return the favor?" Link to comment Share on other sites More sharing options...
bigjayzway Posted August 18, 2005 Report Share Posted August 18, 2005 I am running regular in my 94 Deville, and I set my timing to 5 instead of the factory 10. I get great gas milage, and NO pinging! Big Jay Life is too short to grow up! Link to comment Share on other sites More sharing options...
CaddyChris Posted August 18, 2005 Report Share Posted August 18, 2005 I read a post on another board that had an owner getting 29-32 mph with his 4.9L 93 Deville on the highway. Anyone have similar experiences? You should be able to easily match that with your '95 SLS, Maddog. I used to drive a 4.9 and did nothing to the timing and got around 15.5 mpg driving "normally." I guess doing the timing will further increase fuel mileage. I now have a 94 sts.... Jason, My problem with the Northstar system and basically any powerful car for that matter is knowing what it can do. The best fuel mileage I can get in my 94 on the highway is about 21mpg. Going 60mph with the Torque convertor clutch locked I can get 25mpg on the highway, but that is not realistic. Where I'm going with this is... On my commute to work on the way there I can get 16.5 mpg babying the hell out of my car. On the way back in traffic I take that average down to about 14mpg. It's very hard to relax in traffic...anyone with me? This isn't going anywhere........What I am saying is in order to get good fuel mileage in these vehicles is that you have to baby the hell out of them....IMO once one gets used to the power this is nearly impossible to do. Under WOT in certain situations I think about 2.60 a gallon and I think "well in this situation, that WOT was worth it" so i guess I do it to myself. Anyway, yeah, my point is is that these cars can achieve good fuel mileage but it is very hard to do. I understand it is a little easier in an SLS. Individuals on this board that speak of 17-18 around town is unheard of and I would love to be in the car with them to see how one drives to achieve this kind of fuel mileage because I can't do it. Yes, I'm going on and on here...everyone have a good day. Chris Christopher Petro 94 sts 67 coupe de Ville Link to comment Share on other sites More sharing options...
JasonA Posted August 19, 2005 Report Share Posted August 19, 2005 I think all our cars are just a bit different. I average about 20 mpg in town and I sure as heck don't baby it everywhere. I do drive "smart"...in that if I'm at a stoplight where I know there's another light just ahead or if I'm behind another car, I'll be real smooth. If I turn out onto a two-lane road, I'll lay into it and let it wind out through 2nd gear good (70 mph maybe). I do a good and full WOT at least 2-3 times a week, but I punch it for short bursts at least once a day. I still average in the high teens, up to and including close to 20 mpg. And if you rode with me, I know you'd agree that I don't baby it. My best on the road...a 100% fuel mileage run, is about 32 mpg. I got that by never goosing it to pass a slow car and always driving at least the speed limit (65-70 mph). Some people report as high as 36 mpg, but it may be under different circumstances. Or it may be that their car is just a little less thirsty than mine. The lowest I've ever gotten on a 100% highway cycle was through the mountains of West Virginia, but even then, I matched the EPA's number exactly (26 mpg). For the most part, every SLS owner who's reported here claims at least 25-30 mpg on the road. That's why I mentioned that Maddog should be able to easily match that 4.9L's fuel numbers with his SLS. The STSes do report lower numbers, but it shouldn't be THAT much lower I don't think... It seems to me that your '94 is low enough to cause you to look for a mechanical reason. The EPA rates them at 17/26, even back through 1994 I think. If your average is a good 5 mpg below that, on the highway, I think there may be a mechanical reason for it. But then again, I look back at what I first said (that all cars are different). The STS cars do get poorer economy. Given that, maybe yours happens to be on the low end of the average for the STS cars, and maybe my SLS is on the high end of the average for those, making a direct comparison seem out of whack. Jason(2001 STS, White Diamond) "When you turn your car on...does it return the favor?" Link to comment Share on other sites More sharing options...
Va Maddog Posted August 19, 2005 Author Report Share Posted August 19, 2005 Jason - I do think that you are fortunate to have an SLS that is a little more efficient than some others. Best mpg I have seen is 28-29 on a long interstate trip with the A/C on running about 70 mph. I was happy with that. This past week I had a 600 mile round trip mostly highway driving but some traffic issues - mpg was about 24-25 and that is without much aggressive acceleration. Around town it is between 15 and 18 on a tank full - lots of 5 to 10 mile trips. The higher final drive ratio on the STS seems to knock down the mpg for everyone by about 3-5 less than an SLS. Mike. Link to comment Share on other sites More sharing options...
JasonA Posted August 19, 2005 Report Share Posted August 19, 2005 Jason - I do think that you are fortunate to have an SLS that is a little more efficient than some others. Best mpg I have seen is 28-29 on a long interstate trip with the A/C on running about 70 mph. I was happy with that. Mike, that's what I normally get. Again, I stated that I got that 32 mpg figure on a "full fuel mileage run", meaning I was easy on it the whole way and did everything I could to squeeze every mile out of each gallon while still maintaining traffic speed. I usually get in the 27-29 range...which again (closely) matches the performance of that 4.9L Deville you spoke of. Our cars never cease to amaze me. Jason(2001 STS, White Diamond) "When you turn your car on...does it return the favor?" Link to comment Share on other sites More sharing options...
KHE Posted August 20, 2005 Report Share Posted August 20, 2005 I usually get 27+ MPG on the highway with my '96 SLS. I set the cruise at 79 in a 70 MPH zone. Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
KHE Posted August 20, 2005 Report Share Posted August 20, 2005 That's with regular fuel buy the way. Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
WarrenJ Posted August 20, 2005 Report Share Posted August 20, 2005 What I am saying is in order to get good fuel mileage in these vehicles is that you have to baby the hell out of them....IMO once one gets used to the power this is nearly impossible to do. Ayeyup. That's me alright! Best I've ever done is 26mpg on the (relatively) straight and wide at 65mph with A/C and cruise engaged. 32mpg is simply out of the question, and I've got a small weight advantage on the SLS. I average 20.5mpg overall. My daily commute is 22.5 miles each way with about 5 miles of that on local streets and the remainder on the highway at about 67mph. How a 4.9L equipped DeVille land yatch could get 32mpg is beyond me, but more power to youse just the same. Regards, Warren There is no means of avoiding the final collapse of a boom brought about by credit expansion. The alternative is only whether the crisis should come sooner as the result of a voluntary abandonment of further credit expansion, or later as a final and total catastrophe of the currency system involved. - Ludwig von Mises Link to comment Share on other sites More sharing options...
Ed Hall Posted August 21, 2005 Report Share Posted August 21, 2005 I have my eye out for a 92 or 93 DeVille with the Touring Sedan Package (Actually a unique model) Not many clean ones around anymore as they did not sell a lot of them. Anyone here have one or previously own one? How did you like it? The touring package won't do as well on gas because it has a lower gear ratio transaxle. Link to comment Share on other sites More sharing options...
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