*THE HULL TRUTH is the world's largest FREE network for the discussion of Boating & Fishing. Whether you're researching a new boat, or are a seasoned Captain, you'll find The Hull Truth Boating & Fishing Message Forum contains a wealth of information from Boaters and Sportfishermen around the world.
Welcome to the updated THT!
If you are having trouble signing in, please email [email protected] with your username and we will help you. We thank you for your patience as we help you access the new site!
Random Quote: Rainbow to windward, foul fall the day; Rainbow to leeward, rain runs away!
my late model cars all require 91 octane,but run fine for years on mid or even regular.With modern computers to retard spark,there's no ping or rattle. try it I guarantee you'll agree.
Our Jaguar has used mid-grade since new and I recently tested high-test on several road trips. The reason for testing was that it was only 3% more expensive than mid-grade; so if I got more than 3% more MPG, then it was a good trade.
The MPG increase was between 4-5%; considering that the octane went from 89 to 93 (4% increase).
If the octane you use went from 89 to 91, I can understand why it wouldn't be a good trade.
Since it's a wash, we'll continue to use high-test. If prices go up and the spread remains around 3%, then it will be a good deal for us.
__________________ Rick
Alabama's Gulf Coast
Chaparral 240 Signature (Sold)
wife's Mercedes instantly knows if any gas other than Premium is used. the info is recorded and if any issues arise from not using Premium then the warranty is void according to the service manager.
my late model cars all require 91 octane,but run fine for years on mid or even regular.With modern computers to retard spark,there's no ping or rattle. try it I guarantee you'll agree.
Your statement is pretty broad as it depends alot on what you put it in. Ran out of gas on the bike recently and put 87 in as that is what buddy brought out and it knocked and pinged.
wife's Mercedes instantly knows if any gas other than Premium is used. the info is recorded and if any issues arise from not using Premium then the warranty is void according to the service manager.
I doubt that, premium may be reconmended but the car can retard the timing as mentioned with knock sensors if lower octane fuel is used, there are other factors that could cause the timing to be retarded besides octane rating, so you canot use timing alone to determine if low octane fuel was used. Ask him what technology the car is using that can continuously test the octane rating on the fly.
if any issues arise from not using Premium then the warranty is void according to the service manager.
That sounds like a scare tactic to me. An engine MUST be designed to run on the fuel/gas available locally if the car is sold throughout the world. Doubt they make different engines for each and every country .
I last hi-perf boat was dyno tuned with 89 and 93 octane. Up to about 4,000 rpms the motors didn't care. Above that it would retard timing....alot at WOT. Spinning (2) 540 cubic inch, 700hp motors to 5,600 rpms wasn't worth the risk to save an extra $$$ using less than hi-test fuel.
In a car you rarely push the engine near WOT and therefore driving like grandma with lower octane fuel is probably not an issue....(but I won't do it).
__________________ "The problem with quotes on the internet is that you can never be certain they are accurate"----Abraham Lincoln
It is not a mystery why MB customer satisfaction has gone down for MB. The attitude that MB has aired ruined them from getting my money. My family at one time was 100% MB. No more.
An engine MUST be designed to run on the fuel/gas available locally if the car is sold throughout the world.
Well, sort of. An engine doesn't have to be designed to run on all grades of fuel available locally, just one. Don't know if Mercedes can track octane, but I know one designed for 91 runs like crap on 87 or 89 ...
my late model cars all require 91 octane,but run fine for years on mid or even regular.With modern computers to retard spark,there's no ping or rattle. try it I guarantee you'll agree.
Yes they should run fine on 87 with the spark retard and other automatic computer adjustments - but as s aid below you will get more power with the lower BTU higher octane fuel and could also get better fuel economy due to the efficiencies of being able to advance the timing. I am quite sure I get better mileage with the 93 octane that I am supposed to use than with the 87. With the difference in price now about 2 to 5% - it seems to make sense to me. When the hi test was 10% more it seemed to be a almost a wash.
BUT for sure if your vehicle is designed to run on regular as most cars are - hi test is a total waste of money.
__________________ 1st Cav Div Air Assault Infantry RVN
-Can Do........ and .......Carry On -
My Z06 takes hi-test and def needs it. My charger with a built 440 will ping with crappy hi-test. Hi-test has a purpose and should be used when needed.
Boat is getting about 2.5 MPG. Truck is average around 13/14. Both run on regular. The snowmobiles have a range of 10-20 MPG depending on the sled. The thirsty one requires 91 or better. The fastest one (Yamaha RX-1) is clearly on the high side of MPG but runs on water I think. It's performance doesn't change, it just stays VERY FAST!!!.
The car that I would buy again in a NY second asks for 93 and gets 30/33 MPG.
I got no reason to bitch.
__________________ 2003 Boston Whaler 255 Conquest w/ twin 200 HPDI's
I've never been a racist. I don't like the white half either.
My Lincoln LS V8 takes 91+ and averages 22+ mpg. I can alternate 91 or 93 and 89 at 1/2 tank intervals but the money savings isn't worth the hassle. Man that car hauls ass.
With cars today you can drop the ot rating on the gas but the computer will pick it up and drop your timing back. Less timing means less power.
The meth on both cars is there so I can run more timing than just running 93 ot will allow.
On the vette upping the timing +4 using the meth means 30 to 35 hp.
Cam is cut with +3 also.
Choice is yours but why would you buy a car thats suppose to run on 93 and think you know more than the ones that built it. If the unit is suppose to run on 93 stick it in there. There is a reason they label it that way.
__________________ Triton Tr21x 250 Yamaha Vmax
And a few other toys. ...............
Choice is yours but why would you buy a car thats suppose to run on 93 and think you know more than the ones that built it. If the unit is suppose to run on 93 stick it in there. There is a reason they label it that way.
wife's Mercedes instantly knows if any gas other than Premium is used. the info is recorded and if any issues arise from not using Premium then the warranty is void according to the service manager.
Find a new service manager that knows WTF he is talking about.
Aren't cars (or even boat for that matter) that are designed to run with higher octane gas pretty much made for performance? So why buy it if you need to be cheap about it?
Hi test gas is a money waster! 
. 
1st Cav Div Air Assault Infantry RVN
