Does the type of fuel and engine use determine the OCI?

[chrome]

I was on my way to the airport, and was riding in a Ford Fairlane taxi. The driver told me to guess the mileage on the cab, and I took a wild guess, quoting 600K kms. He smiled, and told me it just ticked over 1,000,000 kms a while back, showing me the digital readout (30+K kms, it had rolled over past 1 million). That's pretty incredible for a 4 year old cab.

Most of the cabs here use LPG (liquified petroleum gas), as it is 1/3 the price of petrol. He goes on a 20K km OCI, using a cheap semi-syn which he buys in 200 liter drums, coming out to AU$3.50 per liter. He says the oil comes out as clean as when he puts it in.

Most incredible of all, the told me the engine has never been open up. Sure, the tensioner bearings do go after a while, but nothing on the inside of the engine has been touched, not even the timing chain. It burns no oil.

I was wondering, does LPG burn so clean, that there is hardly any contaminants that gets into the oil? Very clean oil during an OCI seems to be the norm to anyone running on LPG, versus oil getting black/dark on people running on petrol.

Opinions?

 

[Brett Miller]

2 factors here: LPG does burn extremely clean and the lack of cold starts.

However, that amount of mileage is incredible!

 

[JHZR2]

In the saab 9-3 the default OCI for the diesel engines is longer (by quite a bit) as compared to the gassers. As most GM-LL-025-A oils are also rated GM-LL-025-B (and vice-versa), it seems that the diesels suprisngly get longer OCIs than the gas engines.

Turbo may be a factor - obviously we dont get the diesels here in NA, so I dont have a ful compliment of data.

JMH

 

[Old Mustang Guy]

I drive a CNG (compressed natural gas) fleet vehicle on the job. I notice that even after 7500 mi. the oil looks like new. The fuel burns incredibly clean. It would seem that this would extend engine life.

 

[bighead]

So, could this lack of oil contamination from the fuel burning so clean enable the oil to safely go 2, maybe 3 times longer? Rather, would the additives still be plentiful after a 3x OCI if it's still "as clean as when it was put in"?

 

[WishIhadatruck]

Wouldn't you still be depleting additives and run them out just as quick? Certainly you wouild get fewer contaminates. If contaminates were the issue and keeping you from extended OCI's then it would seem running on CNG or LPG would allow you to run longer.

 

[Curious Kid]

IIRC, nitration concentration levels is a concern, beyond previously mentioned additive up-take and ingested dirt. I would also think that condensate of moisture from combustion is still a concern as well for those vehicles seeing mostly short trips.

 

[Lazy JW]

The sawmill where I work has several propane powered forklifts. Our mechanic recently overhauled one of them that had over 16,000 hours on it. The rings were shot but that's about all that was worn very much. They re-bored the cylinders to .010" over stock bore, I was surprised that pistons were available in such a small oversize. The crank was still good, they put standard bearings back in. It is a Mitsubishi engine. Propane really does help keep an engine clean.
Joe

 

[427Z06]

EU legislation has progressively reduced the maximum sulphur content of gasoline from 150 ppm in January 2000 to 50 ppm in 2005. I wonder if this is why European cars have moved to such long OCI?

I believe we're going through a similar reduction of sulpher content in gasoline here in N. America.