I have used premium unleaded in my 88 240 180k since I first bought it. Recently a friend of mine told me that regular unleaded is actually better for the engine if the engine is not a high performance engine. Anyone have any thounghts, or has has anyone had any problems attributable to either grade gasoline?

I run regular gas with my 91 245SE and its v15 ENEM cam. I have run different grades of gas to see if the timing was much lower than base with the autoretard the computer puts in if it detects knock from pinging, but even going to better grades of gas, I didn't notice anything better with performance.

Another reason mine might not ping is that I run the car very hard, and keep the RPMs close to redline frequently, and thus have less carbon buildup in the engine. If the engine isn't used hard, or attain higher temps, carbon can buildup and cause heat spots that will make the engine ping. If you are having pinging problems, and can only get rid of it with better gas, check your spark plugs, injectors, and get some high rpm driving into your schedule. Revving the car in neutral won't do much since there is no engine load, but if you are on the highway, take it out of OD and get the rpms up past 3-4k. If you are easy on the throttle, anything upwards of 4.5-5k RPM won't do any damage to your engine(depends on how decent your oil and other stuff is up to snuff).

"better"

Cheaper yes, but actually "better"

Can you state his reasons for saying this.

DEWFPO
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1998 S90 068,300 and 1995 964 152,300

For that model, the manufacturer recommends 89 octane (middle grade by US standards). Lower octane pings; higher is a waste of money.

Hello,

Your freind is partially right. Most high-output type engines have premium fuel as their RECOMMENDED staple. However the reality is that manufacturers will specify a minimum octane rating becasue it is what they base the factory engine settings on. So to get the advertised fuel economy and emissions levels one would use that type of fuel.

For the average owner of a 240 including myself, if one was to use regular unleaded the engine would likely start pinging because lower octane fuel burns faster than higher octane. It would also leave more deposits over time as a result of improper burning. I also notice slightly better economy (30-40 km extra per tank) when using premium.

Happy Bricking!!!
--
Richard - '87 245 DL , '82 242 GLT - Half a million km between them!!!

We've had that regular versus premium discussion on the BB before. Apparently the need for using premium varies among 240's. I've had mine for almost four years and generally only use regular. The car runs fine on it.

With the variable timing and knock sensor, doesn't the engine adjust for the octane level? Or is that the case in just the newer 240's?

BTW - every 3K miles or so I treat "Inga" to a tankful of premium and a bottle of Techron. Loves that!! I do agree that the premium makes a slight performance difference but I've never seen a change in mileage. The use of the Techron seems to kill any pinging or deposit build-up. Cleans out the fuel system really well too. IMO - alot cheaper than buying premium.


Jim 90 244DL 233K