when engine is under load it sounds like valves are ticking/rattling

[nsyr]

+1

I have an old porsche that gets 3mpg less with high ethanol gas.

[mconklin]

Originally Posted by Q45tech

The quality of the BEST US gasoline is dismal compared to the early 1990's! The engineers were forced to blend CHEAPER aand Cheaper as the price of oil increased.
The advent of continuous computer controlled streams has resulted in lower and lower BTU per gallon to stretch oil supplies.

The octane number stickers on the pump are meaningless Marketing wishes, all they tell you is a higher number is higher than a lower number.

Blending in ethanol [at the local tank farm] has allowed the refiners to produce really defective grades and make them appear better thanks to the 2.2 -3.0 octane point boost ethanol adds [SOMETIMES].............cheating the standard test under PERFECT conditions.

I agree, my performance varies on each tank of gas I get..sometimes i knock, sometimes I dont..so lame

[bythabay]

all 6MTs do this, it is a known issue with the transmission. Noises can be deceiving

[dkimg35]

Does anyone have this rattling problem in lower revolutions when accellerating? I get a rattling noise in 1st, 2nd, 3rd gear when accellerating when the RPMs are between 1,000 to 3,000. After 3,000, it goes away. Infiniti dealer says it might be pinging from low octane but i'm not convinced. I'm in CA and highest octane i can get is 91. Anyone know if this is really because of the gas and not something else? Engine oil level is fine. Thanks.

[DiGil]

dkimg35, I have the exact same issue. Engine was replaced once for oil consumption, but the new one is fine. I always use 93 octane and still have that annoying rattle when accelerating under ~2,700 rpm.

[nsyr]

+1

My engine was replaced. Didn't do it for about 2k miles, but now it does it all time. Never heard anything about it being the transmission. It sounds like definite engine ping.