8.1 L Owners-What Octane Gas?

[bcfitzsimons]

Alright, guys-

 

How many 8.1L owners out there have to use 89 or 91 octane in their motors to prevent pinging?  My motor's got 15K miles on it, and I've been having a lot of spark knock problems.  Maybe it's just the winter formula gas in Cleveland, but I don't think so.  Do most people use good old regular gas, or do you have to use higher octane?

 

Thanks-Fitz

[4x4man]

I run 85 octane in mine.  No pinging or anything under acceleration.  I do use 87 when towing our 10k lb 5er though, just to make sure there are no problems.

 

Bob

[CMNTMXR81]

My choice fluctuates with price.  Lately I've been putting 89 from Amoco or Phillips in.  Otherwise, I go with 91 or 93 octane.  Admittedly though, in the last few tankfuls of of 89 gas, when I start it up when it's warm, I get a second or two of terrible pre-detonation.  Something that never happened with the higher 91/93 octanes.

 

They may be changing over in Cleveland as they do here in Chicago to their winter RFG formula which may be prone to pre-detonate a little more anyway.

[bcfitzsimons]

That's what the service mgr. at the dealership told me.  I know that RFG is a little more prone to pre-detonate than normal gas, but what about winter formulation makes it more prone too?

 

Fitz.

[chiefsshop]

the gas up north must be different, when I was in Texas I used 87 octane, but now that I work in New York I have to use 89 octane if my foot is feeling heavy or if I'm towing.   I haven't had to up to 93 octane, if I do, there had better be a supercharger ontop of my big block

[Woody1]

when i bought my truck, I exclusively used "above 91" octane. As i found out how much she likes to drink(the lush) i bought a hypertec programmer, programmed to 89 octane and let it "performance tune" my engine. I now run 89 octane only. Here in Iowa we have ethanol mixed in with 89 octane. I havent heard nor felt any ill effects of this in gas mileage, dont get ANY knock and have saved some $$$$$$ in my pocket for not buying that expensive gas. Every now and then when I travel for more than a few hours, I'll dump in some expensive gas cause the price is right. Dont notice any improvement, nor detriment to it by doing so.

[Beaux Duke]

87 works fine for me.  Towing or empty.  Uphill or flat... No problems.

[bummed-n-Md]

87

[HDChuck01]

I use 85 here in Colorado and no problems at all just save lots of money as she is very thirsty!

[bummed-n-Md]

87.

 

One thing I noticed last summer just as winter was setting in, (as the gas stations were 'switching' to winter blend) If I tended to 'baby' the engine, it would ping and knock after a while.  But, when ever I would 'blow out the carbon', the knocks and pings would go away.  

 

What I do now is everyday on the way home, I have this halfmile long uphill road I have to travel.  There is a stop sign at the bottom.  So, what I do is after I cross the intersection, I put the pedal to the floor and accelerate hard up the hill until I hit about 55 or 60 (the local speed limit,  I wouldn't want any tickets).  Doing this once a day seems to keep the engine in good shape all year long with 87 and has almost not impact on my mileage, a constant 10+ in winter and 12.5 in summer.

 

bummed.

 

2002 8.1L/ Allison CC 4x4 shortbed (27K miles in 10+ months)

[Wink]

I have 3500 miles on my 8.1 and haven't heard a ping yet while using Citgo 87 octane.  We're in Florida at this point and I don't believe they do and formulation changes for the seasons.  I had a 6.0 before this truck and it pinged bad on anything below 91 octane.  I tried putting colder plugs in it, which helped a little but it still sounded like ball berings in a washing machine.

 

Wink

[bcfitzsimons]

I think we've got bad gas up here in NE Ohio.  Mine just runs sooooo much smoother with 92, and no pings.  What's funny is that the fuel injector clicks used to be very noticeable, especially when you revved the engine while in park-but now, nothing but quiet.  

 

I don't baby mine either-unless you consider regular maintenance babying.

 

I'm going to decarbonize the engine again with the next oil change, and see if that changes anything.

 

Fitz

[CMNTMXR81]

I've still been using 89 consistently without a problem.

[bcfitzsimons]

CMNT-I thought you said you heard preignition on startup with 89.  Do you still hear it?

 

Fitz

[CMNTMXR81]

I only noticed that on hot days after the engine itself was hot.

 

Since I've put the cooler t-stat and with it being 75 one day and 35 the next, I have not heard a peep out of it.