shotgun_banjo

If you are given a chance to do it again and you will own the GLS for more than 10 years which engine will you choose? The twin turbo V6 or the V8? Why?

chassis

The M276 V6 has a reputation for reliability.

The M278/M157 V8 is developing a reputation for piston scuffing requiring engine replacement.

Transmissions seems to have approx 150k mile life expectancy.

Body and chassis are solid.

shotgun_banjo

Are there any preventive maintenance on the M278 to mitigate those problems or is it given it will happen no matter what? Same as with the transmission. Would doing a fluid change every 60k make it last forever? I wont even go with the "lifetime" differential fluids as there is no such thing.

I have 2 choices right now one with a v6 and one with a v8. The only difference is on the V8 it has ventilated seats and the options are just the same. Wont be towing bit will be loading the truck to the gills with people or gear occasionally. Not sure what to expect on V8 gas consumption but if it close to what I get on my '14 ML350 which is around 19-20 mpg on highway on fully load I would consider the V8. The trick is would the engine last forever like 7-10 years.

WillieMack

Get the V8 and don’t look back. There’s no comparison to the fun factor, appearance, enjoyment, and gobs of torque the V8 GLS550 has over the V6 GLs450.

Both are great vehicles. Quit worrying about reliability, you’re buying a Benz, you’re going to spend money regardless! Might as well get the better vehicle ( A CPO GLS550 with 1 year CPO warranty and email Jeff Jackson JJackson@MBLouisville.com for the best price you’ll find on an additional 2 year CPO warranty extension giving you 3 years of total coverage ), and enjoy that Bi-Turbo V8 with an underrated 516 lbs ft of torque!!

I own both a 14 ML350 and a 17 GLS550. You’d be surprised gas mileage is close on highway!

chassis

Caveat emptor on the V8. Oil changes in my view will not prevent cylinder scoring/scuffing. It’s an example of MB cheaping out on piston and cylinder coating. It wears off then there is direct wear contact on aluminum which is the failure mode.

Yes the V8 is fun. And it guzzles gas and is likely to have scuffed cylinders at high mileage. If those are objectionable to you, skip the V8.

Agree with changing transfer case and front and rear differential oils. Change the serpentine belt at approx 100k miles although MB does not specify to change it. Consider changing upper and lower rad hoses between 100k and 150k miles if you own the vehicle that long.

MB transmissions are barely adequate in most respects. Not bad, however not good. 150k miles for a 7G-Tronic seems when things start going south. I haven’t read a lot about the 9G, it’s still relatively new in the grand scheme of things. The 7G fails in the torque converter, speed sensors and conductor plate (hydraulic solenoid valves). The 9G has yet to show signature failures because of its relative newness.

The V6 has zero difficulty towing and hauling max payload. I have loaded my 3.5L with boat trailer, bikes on the roof, luggage and passengers and it’s a great machine. The 3.0 TT will do even better. Zero concern from a towing and hauling point of view with the V6.

shotgun_banjo

I have to worry about reliability somehow. We have lots of benzes on our belts and all of them stayed in our family for 7-10 years. The longest one is a 09 C300 which is still pouring like a kitty. I maintain the vehicles (most) by myself so it is very important to have a reasonable expectation on what can happen. The ML350 gets around 14-15 mpg on the city but around 20-21 on the highway. From what I read in here people are getting almost the same on the V8 so if that is the case I won't feel too bad going into the pump to fill the tank. This will be tough call....I know I will like the V8 as I had a E550 loaner few years ago and I almost never gave it back.

shotgun_banjo

We will see what will happen next year. I'll call my go to service adviser to ask which they see more trouble on high mileage V8s. I'm literally split here. Both cars are even the same price.

chassis

Does the service adviser work for a dealership?

shotgun_banjo

YES. He is a very good friend of mine. I always ask him and he goes far enough to drag me out of the service desk and talk to me outside and tell me things that someone from a service center should not be telling customers. Last time I needed a battery for my c-class I was at their service center and was about to buy one from them and he handed me a note telling me "buy this at Costco and do it yourself, no need for special hook-up and save you some money". I have things that was meant to be out of pocket expenses that he tried and succeeded getting MB to good will the repairs (the biggest one is my ML350's airmatic. was leaking but got it replaced free of charge even after ELW expiration). The funny thing about it is I asked him if I am sane to get a new GLE or GLS and he said "just lease it or buy the old one. Don't touch anything with the hybrid tech...not yet until they really sort it out."

John CC

I'll second that! I pulled a W126 Diesel on a U-haul car carrier and the performance was impressive, to say the least.

Jt0230

We have a 2017 GLS 550 with almost 100K miles on it, and it's been great to us. It has been reliable to us and the next one we get will be another V8. When we first got the vehicle we were worried about the reliability of Mercedes and we opted to get the 7/100K warranty. I am happy to say we have not needed to use it yet. Let me know if I can answer any other questions about the ownership.

chassis

Sounds like a decent guy. Ask him directly about cylinder scuffing on the V8.

shotgun_banjo

Well seeing that makes a big impression on what the 450 can do. Since you have a blue car what do you think about brilliant blue? with or without night package? I am leaning more towards without as it I think the night package is for white,black and silver cars.

shotgun_banjo

You have note experienced any of the oil wicking to the harness? How about gas consumption? What are you getting after 100k?

John CC

I'm not real big on style. Color is secondary to me, although I tend to prefer interiors that are not black...

We have the lighted star and the fancy Mercedes puddle lights. Is that the night package? If so, it's "cool".

shotgun_banjo

The V8 GLS I am looking as a contender has a saddle brown interior. The night package basically blacks out all the chrome except the chrome moulding on the tailgate and the GLS 450 badge (which is actually odd). Here play around with this website this has night package on the pictures - https://www.mercedes-benz-kingston.c...4matic-id10233 -

John CC

I think our interior is also called saddle brown. I like it. As far as chrome or black, I really don't much care one way or the other. If it was a motorcycle, I might give it a little more thought.

WillieMack

I wanted the night package on my black GLS550. It looks good on white and on a black GLS (especially white with the black contrast). All black night package with tints looks good too, however every one I saw there was a weird purple oxidation fading on the blacked out window trim and roof rails with the night package (heard this was from car washes). I decided to end my search for one.

Blue with night package is a no go. Blue looks better with the silver trim.

shotgun_banjo

Thanks. I was thinking about the same.

silvergl

I just posted a similar question in the x166 GL forum.

Same concerns about reliability. It seems unlikely MB would build a new model with a smaller, slower engine of there were not a reason.

Gregory Thomas

I searched hard to find any issues with the V8's and could not. Anyone have any examples to links for a 2017-2019 GLS550 with an engine issue. I've had my 2017 since March of 2021 without a peep of any issue so far. The previous owner also had zero issues

chassis

Search for cylinder scuffing or scoring. It seems to be mileage related. How many miles on your 2017?

a2j

I don't think anyone can truly make comments about owning a GLS for 10 years. Only time will show. We had our GL for almost 10 years and I would do it again. Not sure about the GLS yet.

skw

Last week we sold our white 450 and a few days ago bought a Cardinal Red 550 w/ the night pkg. I can say that the night pkg makes a difference on the red as well w/ the black roof rails, window trim, mirrors, and wheel accents.

BlownV8

The X166 GL started in 2013 and the GLS was just a minor body and tech refresh. You can look at the early models and determine dependability.