Okay so the manual recommends the use of Premium gas only in the LR4. My wife and I have had many talks about this since getting the vehicle. She figures it's all b.s. and using regular gas would be fine. I argue that if we use regular, we may be voiding parts of the power train warranty and introducing the engine to fuels it's not tuned to and causing stress to the internal bits.

So... which of us is right? Does the LR4 really require top notch gas, or is it all hype?

 

It will run on regular. It will get just a little better mpg on premium, so the operating costs may be evened out. The engine computer will adjust for the degraded gasoline, it computes the engine timing on the fly and spark advance is controlled individually for each cylinder every instant. The top tier gasolines have all the cleaning additives. So long term repair cost may be a little less. Besides, SWMBO is worth every penny!

 

You just spent how much on your new LR4? The cost of putting in premium if you drive 15,000 miles per year and average 14 MPG, assuming a $0.20 per gallon difference equates to a whopping $214 over the course of 1 year. The OEM Continental Tires will pretty much be shot by 20,000 miles. New tires will cost you over $1,200. The gas is a drop in the buck compared to the routine wear and tear items.

Yes, the engines will adjust, but I just don't see the point of saving a few nickels to put in cheap gas. With the old discos, the fuel pump will clog if you use regular.

If she is set on using regular, monitor the fuel economy for a few tanks and then compare it to your mpg with premium. My guess is you'll get a 1 - 2 mpg difference. Premium giving you the better fuel economy.

 

Another thing premium does is make your fuel more consistent. Because in the US, the tank truck heads out to deliver fuel to a station. The station ordered more than their tank could hold (teeneagers can't read a dipstick in car, think they do any better with that long one that goes in the underground tank?). So now the truck has maybe a thousand gallons of premium left. His dispatcher calls other customers nearby - will you take premium at a discount? And that premium ends up in the regular tank of another station. So regular quality varies up/down; as do additives; certainly more often with indy stations. IMHO it is best to buy from high volume stations. Near me all the gasoline for the area comes in on a big barge to our port. Same gas, then mixed with various additives per destination (Shell, BP, WalMart, etc.).

 

Spark and fuel tables are optimized to use premium fuel. That is what gives this vehicle its power curve and fuel economy. Use a lower rating fuel and you will see a decrease in economy and mileage. May also cause an audible spark knock.

Void the warranty? Probably not. Technicians can determine alcohol content, but not Octane rating. However, "top tier detergents" are often only put in the premium blends, and deposits left by lesser gasolines are not covered under warranty.

 

We use premium with LR and BMW that we have.