I fueled up yesterday with premium as usual. It is now sixty cents a gallon more than regular here, thats twelve dollars on a twenty gallon fill. The old VDP is going to have to learn to live on regular. Yeah I'm a cheap old *******.

 

I, too, am a cheap old sumbich, but count yourself lucky. The difference is roughly 80 cents to $1 a gallon in the DC area but weighed against the cost of a burned valve it's a pittance. Don't ask how I know. I hold the cost down with a program called Fuel Rewards which, at least in our area, pairs grocery purchases with Shell gas. I get a base discount of a dime a gallon and I'm often getting 50 cents upward to well over $1.50 per gallon depending on how I structure my shopping and teaming gas purchases with extra discounts the program offers for buying on certain days. I have, on rare occasion, had discounts that slightly exceeded $2 a gallon. Alternatively, Costco top tier premium is roughly 30 cents cheaper in my area against name brand top tier 93 octane, but when you can get $0.50-$1 or more off a gallon a few miles from the house rather than driving 25 miles, no point in using Costco for me.

My two cents is don't risk regular and don't mix regular and high test to cut costs. That was burnt valve #1. I can't remember what the cause of #2 was, but neither were cheap.

Good luck.

 

We in central Virginia have a number of Kroger grocery stores. By signing up to their rewards program, for every 1000 points earned a $1.00 discount per gallon can be had. Currently, premium (high test) is $3.39 a gallon. With the buck off I'm paying the obvious $2.39/gallon. My wife has an account and I piggyback on that account. In our area, Shell is the vendor to local Kroger gas pumps.

My fuel gauge in the '04 XJ8 is very pessimistic. When the low fuel light comes on, I still have 4-5 gallons in the tank; but it's better that I tank up than pushing the Big Cat to Sheetz.

 

Hi to my lucky American Jaguar drivers,
Here in New Zealand, we pay starting at $NZ 2.50 per liter which is equivalent to
Regular 91 RON / 84 MON $US 5.53 / US gallon
Premium 95 RON / 87 MON $US 5.93 / US gallon
Extra High 98 RON / 90 MON $US 6.42 / US gallon

To fill my X358 is usually around $NZ 225 or $US 132.
I'm sure there are places in the world even more expensive.

Pete M

 

I estimate a US gallon of ordinary petrol (gas) at about $7.80

 

To Pete and JagV8: our deepest sympathies. If it is any consolation, we don't have universal health care so we pay through the nose via private insurance. My health insurance bill far exceeds what I pay for fuel for our two cars. You have higher fuel taxes so it's just a question of which pocket the money comes from!

Cheers.

 

I filled up my X350 with lower octane ahead of a long highway drive and the dreaded check engine light came on a couple hours into the drive. The cat was not happy. Have just paid the extra ever since. I think of it as a regular cost of ownership.

 

I doubt it was because of the lower octane, but read the codes.

 

You can alternate between 89 and 93 octane. Spec calls for 91 octane. Not a recommendation but a suggestion. I always go with 93, although more expensive.

 

Ive been experimenting a bit and hand calculating fuel mileage. I’ve tried mid grade 89, premium 93, and 89 ethanol free and haven’t noticed much difference in fuel mileage or performance between these. Never tried regular though. Im a bit partial to running the ethanol free but have run premium last couple tanks. I’d like to try 91 but it’s nowhere to be found in my area.

 

Assuming your engine is in good condition and your engine management sensors are operating properly, the ECM can adapt for regular gasoline/petrol. But it does so by retarding ignition timing, which has the combined effect of reducing both performance and fuel economy. The difference may not be noticeable over the short term, especially if you are a moderate driver. For a lead foot like me, the use of regular represents a false economy.

 

'Too soon we forget.." that an IC engine BUILT for higher octane is as much as fifteen percent more efficient per volume of fuel.

Now.. the PRICE per unit volume premium may or may not keep that where we wish it were, but it isn't as painful as first appears.

And then there is life expectancy and service costs?

 

Lowers working heat captured to turn the wheels & such, raises heat shed into the cooling system, too.

Last thing on God's Green Earth any JLR motorcar needs is a greater waste thermal load to deal with!

 

I'm definitely not mechanically minded so I don't know for sure. A day or two after I arrived in my destination I poured a bottle of octane booster in the tank and the CEL went away immediately, so I chalked it up to cause & effect. Nonetheless, it's premium for me from now on.

 

I wouldn't argue (due to lack of data) but I would:
1. read the codes - they stay stored for ages
2. use OBD to check your fuel trims, especially at idle with a fully warm engine

 

I mix 93 and 87 nearly 50-50, no problems

 

How do you know this is not creating any problems?

 

So effectively you are running 90 octane? Seems for 30 cents more per gallon the risk outweighs the possible damage to the internal combustion and the exhaust system.

Here in central Virginia, our 3 grades are in 30 cents increments. 83-87-93. ($2.85 - 3.15 - 3.45).

Were you to fill up your car at dead empty, adding 22 gallons and saving 30 cents on a 50-50 mix at 11 gallons each of 87/93 is a difference of $3.30? Your call, but my 2004 XJ8 is my daily driver and I do not skimp on fuel, tires or brakes.

 

People frequently claim that their cars that requires premium runs fun on regular. Well, modern cars have knock detection, and when a knock is detected the ECU retards spark to reduce knock. But, it’s still there. So, you get reduced performance, and still get slick knock. I’d find other areas to save money.

 

It will easily survive a tank or just a top-off once in a while with regular gas, but I would never use regular gas as the only gas! The damages (rod bearings, valves, etc.) from full-time regular gas in an engine that is built for premium, and the knocking it will produce, are so obvious that manufacturers will deny warranty coverage while the car's in warranty. You'll never convince me that the car can adapt to it long-term!