I bought a 93 940 last month. The owner's manual says premium gas. My 89 240 takes regular. Both cars have the same engine. What am I missing? Does everyone put premium in their 940s?
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89 240 190K, 93 940 80K

I smell a conspiracy brewing here; shades of GM and the oil companies.
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John Shatzer, '97 V90 @ 105K

Honestly not so with me. I am actually more of an environmentalist and definitely no fan of big business. I went to U.C. Berkeley, so that may give you a clue.

What I've said is based on my own experience in 32 years of driving & working on cars.

The newer engines are designed with compression ratios, cams and computer controls to run more efficiently on higher octane fuels. If you run lower than recommended octane gas:
o It may ignite improperly which in turn results in pinging which causes the knock sensor to retard the ignition to reduce it (you won't hear any pinging unless it's really bad) which results in loss of performance (and fuel economy)
o It may burn less completely hence more emissions (more lost fuel economy)
o It usually gives you a gas containing less cleaner additives which allows more engine deposits to accumulate which in turn affects ignition and emissions as above.

Within reason your car will run on pretty much any brand and octane you give it, but there are tradeoffs:
o The environmental tradeoffs of improved fuel economy are pretty clear. As the auto industry is highly governed in this regard you can be sure that's the major driving force for manufacturers' deciding which octane to recommend. Then of course there's the oil companies helping all this by wanting to sell the more expensive and presumably more profitable higher octanes.
o The performance tradeoff is also clear -up to a point, higher octane gas in a properly maintained engine will give you a peppier car. This factor is quite noticeable when I drive a heavier 700/900 car with the basic B230F engine.
o The economic tradeoffs are maybe not so clear. Regular gas is cheaper, but you get lower gas mileage. Higher octane gas is more energy intensive to produce. You probably also increase engine wear and tear a little. I have no idea what the bottom line dollar impact is.
o Gas that is ethanol blended may speed the deterioration of some rubberized engine seals, although rubberized materials have been improved and blends kept to a maximum of 10% ethanol (the trigger point for a U.S. federal tax break). I'll bet a cool one that those original little rubber hoses between the in-tank pre-pump and the pick-up tube that disintegrate on some 240's aren't helped by this.

Now, cheap SOB that I am, I have a couple of tactics. On long highway trips I tend to use gas that's 2-3 octane points lower than recommended. I figure it saves money without appreciably lowering combustion efficiency at those higher rpms and, having a turbo, I still have more than enough pep. I live in a region where perpetual gas wars often see the price discounted by 10 cents/litre or more (40 cents/gal) every week or two. The discount is disproportionately deeper on regular gas than the higher octanes (obviously because only regular gas prices are usually posted on station signs). So, if I want 91 octane, I'll sometimes do my own blend of 3 parts cheap 87 octane to 4 parts 94 octane for a net saving of about 3 cents/litre (12 cents/gal) when a gas war is on. I don't know how much of this is false economy, but I do feel better knowing I cheat the oil companies and tax grabbers out of a few bucks a week.

My 940 with turbo runs fine on regular. If yours runs on regular without pinging you are just wasting money by using high test. If your car runs fine on regular but you believe it runs better or gets better mileage on premium, just try washing and waxing car, they run better when clean, seriously save your money.

JJ

Per my other posts you can see I disagree.

Pay me now or pay me later is true for the costs. For power, premium is better.

Good job. I should have mentioned the environmental aspects myself.

I occasionally (on long trips) do the blending thing myself.

Volvo says it will run best on 91 minimum. I have used premium (good premium, not the stuff at gas-and-go, etc.) for most of the 32 years I have driven and worked on cars. I have never had a burnt valve, virtually no deposits on the pistons, in fact only had to do a valve job once, after 190,000 miles on a Pinto. When I have tried regular, I noticed a difference in power and the gas mileage went lower (though not by much).

The 940 and all Volvo's cars with an ECU will run on regular without pings or engine damage. The computer will compensate to allow this, but there will be a power loss.

There is a difference amoung different brand gasolines. Yes, it is true that often the base fuels OF THE SAME SPECS are blended together at the terminal, which blurs the difference in brands, but there is still a diffence in the additives that they blend in as the tanker trucks are filled.

That was the long answer. The short answer is that you can use any octane you want in most Volvos with an ECU.

Is this a turbo, if so I believe it needs premium. My '93 940 NA runs fine on regular.

Mine (Regina) runs fine on 87. No pings, knocking or other symptoms. Good mileage too — as high as 32+ mpg on secondary roads with A/C off and 35 psi in new Conti tires last spring.
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Bruce Young,
'93 940-NA (current) — 240s (one V8) — 140s — 122s — since '63.

My 93 940 turbo runs much better on premium.

...runs fine on regular fuel..but i haven't really tried putting premium in her..might try it to see the diffirence...


91 940 SE
158+ miles, AW71, Mitsu 13C

according to the factory manual on the lh 2.4/ezk 116 fuel ignition manual dated 3/93, all b230fs require 91 octane. good luck, chuck.