On the contrary. You should sell your other cars. They will lose over 20% of their power at all engine rpms compared to sea level. Your S560 will also lose over 20% of its power at low rpms before the turbos kick in, but then less once the turbos spool up. Nothing kills performance quite like elevation, especially in naturally aspirated engines.

https://calculator.academy/hp-loss-a...de-calculator/

 

Oh sh...selling the other cars would really be a problem since my wife is really in love with, at least, two of them !
Anyway, thank you for this interesting feedback !

 

Unfortunately over the years I met some pretty irresponsible people that leased various cars or trucks and just didn’t give a hoot the cars or who would get them next. Barely did any maintenance, used cheap gas, seldom washed their cars. To this day I wont look at a leased car unless it was part of a corporate fleet and has a good CarFax. And Florida cars - as I was told many times from several unrelated sources that Florida people tend to only care about how good the car looks more than the maintenance. It’s funny that the Carmax general manager mentioned this very same thing this past Thursday night.

 

Well that’s out, I might as well sell the car if I have to travel 30 to get top tier fuel every week. I looked up the locations and they are few and far between.

 

Really? You live an hour from Philly and you don't have major brands nearby? Shell, Chevron etc are all TOP TIER brands. Even Cosco is TOP TIER.

 

Might as well.... you've been looking for a reason not to like the car since you got it....

 

That is a shame, the W222 is a nice all rounder and commuter, why buy something that you kept on wanting to sell in the first place : (

Hopefully OP figures out the fuel situation and find things to enjoy about the car, which is a lot to enjoy if look carefully enough.

 

Just buy the best gas you can find, name brand gas and you will be fine. You don't have a Shell or an Exxon or a Mobil or a Sunoco or something like that?

 

CA only has 91, I have run some octane booster a few times but really didn't see a difference. There is a station that sells "race gas" at 98 I was thinking of putting in 5-6 gallons and the rest 91 to see if there is a difference. I have run Costco gas for over 25 year in all my cars and had fantastic results, no engine issues really ever over 4-5 cars including my 84' 300ZX that I bought new and really only runs Costco.

 

As I explained above, with stock engine maps you won't see any difference going above 91 and you are wasting money on octane boosters. Those higher octane fuels only provide benefits with aftermarket tunes and corresponding engine maps. For a track car with an aftermarket tune that has a race gas map, you can extract more performance filling it up with race gas and then selecting the corresponding map in the tune. Just make sure you change it back to a lower octane map when filling up with pump gas again, otherwise the engine will start knocking.

 

Keep the S560. Its turbos will help at altitude. Anything forced induction will help. Sell the others if they struggle going up hills or lack power you need.

 

Premium gas looks like give me a better performance especially if you have bi turbo engines .I don't know whether or not it's a placebo effect but it should not be like that . A well known brand is my preference . Higher octane = better acceleration but difference between 91 octane and higher is less palpable than difference regular gas vs premium

 

You can’t put regular gas in one of these, nobody is suggesting that.

 

I just found out QuikTrip has top tier gas surprisingly. If it’s in your area.

 

Yeah that's what I've heard. I've also recently removed Sheetz from my list as I found out they are NOT Top Tier gas.

 

I don't use Sheetz either...

 

Anyone keeping that as a surname doesn’t lack for confidence.

 

I never had any issues with unbranded gas. What I do try to avoid especially in flood prone areas is older unkept gas stations for fear there could be water in the tanks. All stations have a little bit of water in the tanks which sinks down to the bottom but when the station operator lets it get out of hand and it comes up over 5 or 6 inches thats when there could be a issue, the pickup lines in the tanks at the station are generally at least 5 or 6 inches from the bottom of the tank. For the most part there is not a difference between unbranded and branded gas as they all come from the same terminal. I use to own unbranded stations, sometimes would get gas from the shell terminal other times from the mobil terminal.

 

The gas isn’t different, but the additive packages are different.

 

No name gas as long as it's Top Tier:

https://mbworld.org/forums/s-class-w...ml#post9047294

Top Tier Fuel Post and Research Synopsis



Prior to finding this article, I thought octane rating was the most important factor in which gasoline to choose and use. I had been told by a fuel delivery driver that all not premium gas was the same; literally pulled from the same tanks and nothing was different regardless of brand. He told me that the only difference was in premium gas, where each brand puts an additive in the gas that’s in the storage tanks at the distribution center, not in the truck or at the gas station. My choice in fuel to purchase was based on this, and it’s not accurate. It might have been accurate at that time, but is not the way gasoline is distributed now.



Top Tier fuel has nothing to do with Octane levels, the 2 are totally independent. Information from Report: “Some consumers may associate gasoline quality with fuel grade (premium vs. regular) or octane number, which is a mistaken assumption. Motorists should use the fuel grade recommended by the vehicle manufacturer in the owner’s manual.”

Summation regarding octane: Gasoline doesn’t “burn” in an engine, it actually “explodes”. Gasoline’s special quality that makes it the perfect fuel for ICE is how it explodes under heat and pressure. The spark from the plug ignites the mixture at the optimal time and piston position. Octane level, or octane rating, measures how resistant a fuel is to premature ignition, or "knocking", in an engine. Further explanation: “Octane ratings are measures of fuel stability. These ratings are based on the pressure at which a fuel will spontaneously combust (auto-ignite) in a testing engine. The octane number is actually the simple average of two different octane rating methods—motor octane rating (MOR) and research octane rating (RON)—that differ primarily in the specifics of the operating conditions. The higher an octane number, the more stable the fuel. Retail gasoline stations in the United States sell three main grades of gasoline based on the octane level:

• Regular (the lowest octane fuel–generally 87)
• Midgrade (the middle range octane fuel–generally 89–90)
• Premium (the highest octane fuel–generally 91–94)

The goal of the study was to see if the additives in Toptier gasoline actually helped reduce carbon buildup on intake valves. This study was NOT about fuel economy or performance. It can be argued that you could expect better performance due to a cleaner fuel system, but there was nothing in the test that talked about economy or performance increases or efficiency. If that was the case, then why do the study?? In a lot of today’s engines, the fuel injectors spray fuel directly into the combustion chamber instead of into the intake port. GDI engines spray atomized fuel into the combustion chamber. Port injection (PI) engines spray fuel into the intake ports. Since PI engines spray fuel into the intakes, the fuel cleans off carbon deposits from the back and head of the intake valves. On GDI engines this does not happen. Therefore, GDI engines can suffer from carbon buildup on the back of the intake valves, reducing efficiency and causing even more carbon buildup over time. Over time carbon buildup can cause:

· Reduced engine power

· Poor fuel delivery

· Valves sticking

· Damaged valves or pistons

· Rough idle, misfires, and increased emissions



In the case of the M177/M178 engines the increased emissions will cause the oil separators to clog, which leads to increased crankcase pressure and eventually leaking valve covers, or the dreaded rear main seal failure…OUCH!!! That means a very expensive repair.



That’s why it’s important. Having said that; it’s only relevant to GDI engines. They tested different Toptier gasoline to see if they in fact helped to reduce carbon buildup and to also remove existing carbon buildup. All gasoline used in the test was Premium 93 Octane. Excerpt from report:

“Premium fuel (93 octane) was selected as the octane grade for this evaluation due to the trend of some brands to put a slightly higher concentration of detergent in their premium grades of fuel. Even non-TOP TIER gasolines may include additional additives in their premium grades, so this choice in octane was intended to eliminate that variable. Retailers that sell TOP TIER gasoline are required to meet TOP TIER standards in all grades of fuel, not just premium. For TOP TIER gasoline, the test results (fig. 8) should be consistent if the test was conducted with regular grade gasoline. Testing non-TOP TIER brands of regular grade gasoline would likely result in similar or higher levels of carbon deposits on critical engine components.”



You can read about the methodology and test parameters, but I wanted to tell you what I thought was important.

The additives in the gasoline are designed to:

Clean the injectors as they flow through the fuel system

Survive the combustion process and get into the crankcase oil through normal blowby. Then flow through the EGR system and clean the valves as they are returned into the combustion chamber.



The additives actually did that, and that’s amazing!!



In order to make it fair, they tested Toptier fuels and non Toptier fuels. Here’s an excerpt of the results:

4.3 Test Results

The weight of the intake valve deposits was measured with a high accuracy lab scale. The weight of the deposits on all four intake valves were averaged into the values shown below (fig. 8) to represent each brand of fuel. The non-TOP TIER gasolines resulted in a group average 660.6mg of deposits per intake valve. The TOP TIER gasolines had a group average of 34.1mg per valve or roughly nineteen times fewer deposits than the non-TOP TIER gasolines.



Lastly; who did the test and was it objective? This was an objective test performed by the American Automobile Association, AAA, or Triple-A. They tested to see if paying the additional cost at the gas pump was worth the extra money. In their opinion, it was. In their report, they stated that Toptier gas cost $.10 cents per gallon more than non Toptier. That’s not the case where I live, but they bought gasoline in Texas, and tests were performed back in 2016. Also, consumers have the choice of purchasing fuel system cleaners over the counter, and it has the same effect. The ingredient that does the most work is PEA, along with some other compounds.