K75rt gas ?

[scoobs]

I've been running my '92 K75RT on regular unleaded but a friend thought I should by using premium instead. Will it improve my MPG return, am I harming the engine by using the cheap stuff? The bike has covered 109,000 miles and is a smooth runner.
Anyone have any input on this?
Cheers,
Ian.

 

[roncooper]

87 for me. Premium doesn't help.

 

[41077]

I have alway used regular, occasionally springing for a tank of Chevron or other "high end gas" that claims to clean fuel injectors. Never had a fuel related problem, save your money.

 

[kgadley01]

I've always used premium in all my bikes. Being cheap will come back on ya.

 

[breyfogle]

Run the lowest octane that does not ping and you will be fine. Higher octane than you need is just a "feel-good" waste of $$$.

 

[35634]

Since BMW got it's start making airplane engines, I always run avgas in mine. Yeah, it's throwing $$$ away but I'm staying true to the philosophy of Big Money Wasted

 

[bikerfish1100]

Run the lowest octane that does not ping and you will be fine. Higher octane than you need is just a "feel-good" waste of $$$.

Ding! Ding! Ding! We have a winner. The only accurate and ultimately fact based answer. Everything else is pure unsubstantiated opinion.

 

[WalterK75]

I have a 1991 K75RT. I find using a higher octane makes the engine more responsive. Had the same experience riding a R1200RT; higher octane better performance. Try it and compare. If you feel no difference, then use the lower octane.

 

[PHMARVIN]

Hi,
BMW themselves recommend regular fuel. 91ROZ octane is the recommendation and it corresponds to 87 pump octane here in the USA. Yes, the bike will run fine on premium, but it will cost you an additional 20 to 40 cents per gallon and get you no better mileage. The only benefit I can see is in a few places the premium unleaded is 100% gasoline, not the 90gas/10corn squeezings most of us get.

 

[lee]

am I harming the engine by using the cheap stuff? The bike has covered 109,000 miles and is a smooth runner.
.

The 109,000 miles pretty much answers your question

 

[WalterK75]

From Rider's Handbook for K75, K75S, K75RT:
Type of fuel: Unleaded premium grade fuel DIN 51 607, minimum octane number 95 (RM) and 85 (MM)

 

[pglaves]

My '86 ran 370,000 miles on regular. That is what was called for back then with real gas. Our seven or 8 other K75s have always run fine on regular too. I'll have to check the book on my '94 and '95, but they don't ping at all on regular.

 

[PHMARVIN]

Hi, Paul,
I just checked the owner's manuals on both my '94 K75 and '95 K75RTP. I was surprised. Both call for mid-grade fuel. It actually says 95RM (research method, 85MM (motor method) or mid grade 89 anti knock index. Like you, I have never heard a ping while using regular unleaded fuel (86 anti knock index where I live). I don't expect I will start using higher octane fuel since I have many tens of thousands of miles on K75's using regular unleaded. In fact, even though I normally used premium, the times I used regular unleaded in my K1100LT's, I never heard any pinging, either.

 

[scoobs]

Thanks

Wow, you folks were quick off the mark on your replies !! Thanks for the input, I'll stick with the regular gas- if its good enough for the venerable Paul Glaves then its good enough for me !!
Ride safely,
Ian.

 

[wavery]

Run the lowest octane that does not ping and you will be fine. Higher octane than you need is just a "feel-good" waste of $$$.

Out of curiosity, is pinging an indication of damage to the engine, or just a nuisance?

 

[breyfogle]

Your engine will not like persistent, long term, pinging. See ...
http://en.wikipedia.org/wiki/Engine_knocking

 

[35634]

some more sophisticated ignitions systems retard the timing when the knock sensors detect pinging. Thus you could get better mileage and performance with premium, but not get pinging with regular, though you would loose some efficiency. This is getting off topic, the early K's were not burdened with such technology.

 

[bikerfish1100]

Out of curiosity, is pinging an indication of damage to the engine, or just a nuisance?

pinging is the "sound" of damage being done to your engine. more frequent pinging, more damage. downshift is your immediate response, higher octane gas is your distal cure.

 

[wavery]

Your engine will not like persistent, long term, pinging. See ...
http://en.wikipedia.org/wiki/Engine_knocking

pinging is the "sound" of damage being done to your engine. more frequent pinging, more damage. downshift is your immediate response, higher octane gas is your distal cure.

Thanks for the info.

 

[ted]

Is Jetronic smart enough to keep the delayed detonation from higher octane (91+) gas used in moderate compression engines from leaving carbon deposits? As for 87 v. 89, I usually use 87 though the manual looks like it recommends PON 89. For a regular dose of cleaner I either use the maintenance dose of Stabil Blue or Chevron's Techron.