Why 20.8 mpg-1510 miles-1998 Suburban-Gift horse in mouth??

[phoebeisis]

I bought my 1998 Suburban with 1995 miles on it about one year ago.I had a Chevy/Toyota car before-Prizm-and it gave good service, but if I hadn't had money problems I would have never considered buying a vehicle,any vehicle,with 195,000 miles on it.I bought the Suburban because I needed something big in case we-3 adults,2 dogs,4 cats-needed to evacuate from New Orleans.It was cheap-$2950-and in good shape with a recent trans rebuild,rebuilt AC system,intake manifold gasket,rebuilt alternator etc. The PO didn't stint on maintenance, but 195,000 miles is a lot of freakin' miles.

It gave surprisingly good service in the last year-never left me on the road in 3500 miles of pure city driving.I replace the Radiator,water pump,brake booster, belt tensioner-about $500 in parts,I do my own labor-I work cheap,and really couldn't afford to have a mechanic do the above-cost maybe $1500 total if I did,since I get parts off ebay or online, or autozone(waterpump belt tensioner).

I drive to get good mpg-belong to cleanmpg- a hypermiling forum.Driven extremely carefully I get 14 mpg in pure city driving( 2wd 1/2 ton)-better than I expected-I expected maybe 12 mpg or less.

My gift horse in the mouth is we just drove from New Orleans to Flagstaff AZ-1510 MILES.I drove at 68-70 mph with the Cruise control on-no tricky hypermiling techniques.Tire pressure 42 psi-Mobil 1 5W30. I got 20.8 MPG-WAAAAAAY better than I expected,and much better than I've ever seen claimed with the 5.7 Suburban.I expected about 17-18 mpg at the 68-70 mph we drove.

I always look gift horses in the mouth-why did I get such good mpg?? It is 7000 feet uphill which hurts mpg.I suspect that the prevailing winds are actually going the wrong direction to help.We have done this trip 10+ times before and always get better MPG on the return trip.We took I-10,-I-49. I -20 to DWF,Hy 287 to Amarillo, I-40 to Flagstaff.

Anyone ever hear of the 5.7 Suburban getting this kind of mpg at 70 mph?? Maybe the loose motor helped the mpg-well worn in.I had considerd trying to sell it to get a newer 5.3-better mpg and better brakes,-but no money hurt that idea,and my Suburban would be nearly impossible to sell for more than $2000-worth more than that to me, of course.
I used about 12 ounces of oil over 1500 miles-not bad.

Any ideas why I got close to minivan mpg with a kinda old heavily used Suburban? I had a small carrier on the back,and maybe 800 lbs of humans,dogs and cargo.

Thanks,
Charlie

[vncj96]

not unheard of my parents second suburban was a 1992 1/2 ton 4x4 and we went from MN to texas with 2 adults and three children between 12 and 17 for two weeks and pulled 21 the entire trip, and that was at 70mph for most of the way, now that suburban had a 44 gallon tank and wa plenty of time in between fillups to help maintain a steady speed which helps greatly

[phoebeisis]

vncj,
Thanks for the response.I expected maybe 17-18 mpg because that was what my buddy-a mechanic and big GM booster told me I would get.He might have been guessing a bit low intentionally just so I would be really happy with the result.He didn't expect almost 21 mpg of course.I did this trip 6 times in a Honda Pilot(the vehicle I had to sell for $15,500 because of $$ problems,and the vehicle I replaced with the Suburban,$2950).The Pilot got 22.25 mpg-same trip-at very slightly higher speeds(maybe 72 mph). It was a pretty efficient vehicle with a 5 speed auto,3.5 lt V-6,and 1000 lb less weight.I expected it would get maybe 4 mpg better than theold,high mile Suburban.Pleasant surprise that the Suburban gets almost the same mpg, but has about 50% more interior room behind the front seats.We don't stay in motel rooms;we sleep in the back of the vehicle at rest stops,so lots of room is a HUGE plus.Nothing beats big for traveling long distances and sleeping at rest stops(much cheaper than $80/night motels-free!)

If our finances improve, maybe I can buy a 2002 with 70,000 miles for $8000 or so.Currently you can get them as cheap as $10,000 for a 2002,69,000 miles with leather and all the BS stuff.We have a dog,so leather isn't something I care about.I just like the power driver seat,and power mirrors.The rest I don't care about.

Gotta admit,the Suburban has been a pleasant surprise.We needed some good luck.
Yep,this one has a 44 gallon tank, but we stop about every 2-3 hours to stretch,walk the dog,use the facilities.
Heck,with this mpg we could make the trip with just one fillup-heck we could cross TX in any direction without a fillup since the range is about 920 miles!

Thanks,
Charlie

[Robinson76]

Lol If I was getting 20mpg, I wouldn't be asking questions,
I would be too scared of Jynxing myself next time lol

But have you considered climate?
altitude and temperature?

[phoebeisis]

Robinson76,
Good point,I shouldn't look this horse in the mouth, but it was sooo good,I'm looking.

Altitude-we gained 7000 feet-does improve mpg-less aero drag, but we also gained 7000 feet which hurts mpg.
Warmer temps help a little-to a point. Very cold gives poor mpg-70 degrees or so probably gives the best mpg.It was 85 or so which means we ran the AC constantly-not a good thing for mpg, but probably not too big a deal with a V-8.

Wind might have helped,but I don't think so.We have done this trip many times,and we get 1-2 mpg better on the return trip.I think the prevailing winds are usually from the west.I'll know for sure in 5 days,since we will have done the return trip and be home Sunday night.

My best guess is that this Suburban just gets good mpg if you keep your speed at 70 mph or less.The tire pressure-43 psi,- and the worn tires probably helped,and the 3.42 rear end sure helped.Maybe the 5w30 Mobil I helped a tiny bit,but not much.The worn in motor probably helped a little.

Bottom line it gets very good mpg for such a huge comfortable travel vehicle.Not so great in town-13-14, but awfully good on the road.

You have the 5.3-good for mpg-but the 4x4, 6" lift,35" tires with aggreessive thread are all killers mpg wise.I would expect maybe 15 mpg at 70 mph with your setup.Not bad considering the lift and tires and 4X4;fun truck of course.

This is the best $2950 I ever spent-minivan mpg from a Suburban I could strap my motorcycle on the back of(I didn't but I will next time).I did add Bilstein shocks-$210 Ebay because there was way too much wallowing and pitching around turns-didn't really hurt the ride any.I like a soft ride.The stock shocks were shot.

The return trip will settle the wind question, but I'm pretty sure it wasn't the wind.I got the best mpg heading north in the 1st 350 miles(22.3 mpg).None of the runs were less than 20 mpg.
Thanks,
Charlie

[sysmex]

I sold my 95 Blazer 4x4 six months ago which I loved due to kid #3. Just not enough room! I bought a 99 Sub and I love it. I haven't done a road trip yet, but so far I've gotten 13.77 MPG at best in the city. My Blazer would only give 15 MPG. ( not a bad compromize). I can't wait to see what it gives in the Highway. I LOVE CHEVY!!!!

[vncj96]

I sold my 95 Blazer 4x4 six months ago which I loved due to kid #3. Just not enough room! I bought a 99 Sub and I love it. I haven't done a road trip yet, but so far I've gotten 13.77 MPG at best in the city. My Blazer would only give 15 MPG. ( not a bad compromize). I can't wait to see what it gives in the Highway. I LOVE CHEVY!!!!

My 99 suburban isnt as good I get 14.5 right now with city and slight highway, but to get to my work i have ahuge hill to climb both ways and that is killing the MPG, just gave it a tune up so will see, but last year took a a good road trip to northern MN and got 16.5 and that was with town driving when i got to my destination, this year will be different so i hope to get at least 17. all the computer stuff hampers it i think, compared to the old TBI that the 92 had, but a programmer will help when i get the cash, will keep everyone posted.

[Steve]

I sold my 95 Blazer 4x4 six months ago which I loved due to kid #3. Just not enough room! I bought a 99 Sub and I love it. I haven't done a road trip yet, but so far I've gotten 13.77 MPG at best in the city. My Blazer would only give 15 MPG. ( not a bad compromize). I can't wait to see what it gives in the Highway. I LOVE CHEVY!!!!

City driving is the worst. All vehicles get bad city mileage.

[hunky]

My '98 tahoe 4x4 won't get more than 17.5 mpg if I drop it down a mineshaft. The '97 crew cab (centurion conversion) I had always got 20mpg on trips. Same 5.7 motor, must be the AWD transfer case?

[phoebeisis]

Guys,thanks for the responses.

Sysmex-you are probably in for a pleasant surprise.I get about 13.5-14 mpg in pure city driving -driving very carefully with pulse and glide . THE RETURN TRIP WITH MY 1998 SUBURBAN GOT 21.8 MPG!! I'm pretty happy,and a bit surprised .Over the 3021.7 mile trip I got 21.3 mpg at 70 mph-cruise control on.I used just 141.7 gallons over 3021 miles.You get about the same city mpg I get,so I expect you wil get about the same highway mpg.Keeping your speed reeasonable-cc on 70 mph-despite 75 mph limit in AZ,and NM-really helps.

I used 42 psi tire pressure on all 4 wheels to get better mpg-ride is still pretty soft-Suburbans ride nice and soft.I also use Mobil I 5w30 syn oil-it probably helped a little.I used about 24 ounces of oil over the trip-not bad for a 202,000 mile motor.I considered the Mobil I 10W30 high mileage oil, but decided I would stick with the 5w30-gets to the motor more quickly when cold-probably caused a little more oil use, but so what?

Keep stuff off the roof rack.Use a hitch carrier for ice chests, bikes etc.

Hunky-yeah, it sure is odd that 4X4 and AWD can cost so much mpg wise.I wouldn't think that moch more was turning when in 4x2 mode, but guess it is.

VNCJ96-Yep city driving and hills just kill mpg.In Flagstaff itself I used 6.2 gallons in about 85 miles-13 mpg and change. I don't count the miles once I get there-just the "trip driving."

I'm really pleased, but I'll probably attempt to sell the Suburban. I'll probably ask $3800, but I don't expect to sell it(despite the rebuilt trans,new radiator,water pump,belt tensioner,brake booster,alternator,AC,intake mani gasket etc). Suburbans are tough sells now.
Now if it did sell,I would hunt up a 2002 Suburban with under 90,000 miles.They are selling for as little as $8000 (ebay houston dealer,and locally).I would love to have the better brakes, and the slightly more efficient 5.3. and side airbags.Kinda short of $$,so no way I can buy a 2002 without selling the 1998.

I doubt it will sell,so when I get the $$,I'll buy a new Goodwrench 5.7-about $2500 delivered.With fluids.gaskets etc it should be about $3000 all total.It will probably take me 2-4 weeks to pull and install it.The current motor is awfully FE, but since we drive long distances,I would like the security of a new motor.

Can't really beat the Suburban for traveling.We sleep in the vehicle-at a rest stop in TX off Hy 287 near Quanah, or Chillquot??-while enroute to Flagstaff. No motels while enroute-save $$.We ran the AC for 6 hours while sleeping- It used about 4 gallons(I have a Scan Gauge that tells me gallons used).I measure my actual mpg by dividing the real odo distance by the real gallons I put in.Nav displays frequently are wrong in respect to mpg-they say you get better than you actually get. If I counted those 4 gallons I used while sleeping it would drop the trip mpg to 20.7. 4 gallons of gas($16) is less than the $50 for a cheapo motel.

Hey anyone want to buy a 98 Suburban-ALL HIGHWAY MILES(ha,ha)?I suspect I'll drive this one until it turns to dust.
Thanks,
Charlie
PS-for hypermiling tips go to cleanmpg.com folks there are generally nice.There is a lot of talk of FSPs(fuel sucking pigs) which means our Suburbans, but the most adept there are the most polite.I've never been flamed despite my mentioning my Suburban many,many times.I also have a more traditional mpg type car-Prius-but I can't drive a Prius on a 3000 mile trip with 2 adults,dog,,ice chests,bike,pillows,mattress etc.
The basic stuff is easy-tire pressure,pulse and glide, shut off at redlights,syn oil,keep speed about 60- 65 mph on interstates(I do 68-70 usually) stay off the brakes-glide to the redlight. Your vehicle and brakes will last longer.I don't do the exotic stuff-shutting the motor off while driving-not for me.It works, but too much for me.Good tips there. Nice folks-some are a bit preachy, but so what-they aren't your brother in law!