Solving the Problems of the Carrier
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Oil or Petrol for 30 m.p.h. Lorries?
The Special Conditions of the Times Favour the Oil-engined Vehicle and " S.T.R." Gives Some Comparative Facts and Figures Which Point to its Economy of Operation and Correspondingly increased Profitable Working
LATELY I have had a number of inquiries from operators asking me which I would recommend, oil or
petrol, for 30 m.p.h. lorries. Sometimes I am asked whether I would recommend an oiler, having in mind the considerably increased first cost and again, sometimes, what is the net economy to be expected from the use of an oil engine, when all factors are taken into consideration.
There is undoubtedly ,a keen interest just now in this problem. Part of this has arisen, no doubt, from the fact that manufacturers of this 30 m.p.h. type of vehicle which ' have, hitherto, confined their attentions to petrol engines, are now offering oil units as alternatives.
There may he something behind that tendency. It may be that those in authority have decided that to keep this country's road transport going would need a considerably less tonnage of shipping 'if all the vehicles ran on oil fuel than if they all used petibl and that, therefore, the more pil-engined lorries on the roads the less would be the demand for shipping. It seems rather surprising that it has taken four years of war to bring that obvious' fact to light, but there it is.
One inquiry, in particular. I must refer to more specifically, because it indicates a certain confusion of mind and-a lack of appreciation of realities.
This inquirer stated that he had been offered a " 13 " lorry with an oil engine at 2,1,050 and a '7C " lorry with .a petrol engine at 2450. It seemed impossible to him to make up that difference in first cost•by savings in expenditure on fuel and he asked me for my views.
Important Factors that Account • for the Difference in Price There are two matters of importance involved in the ,price difference and my haulier friend was thinking of only one. He had overlooked the fact that the oil-engined vehicle was much more substantially built than the petrol. engined vehicle, and that the difference of £600 in price was, in part, due to the increased cost of the oiler, but also to the better quality of the., chassis. He could hardly expect to make up in fuel savings for that portion of the difference which he was paying for a better-quality vehicle. Before, therefore, tackling the problem which is presented, it is essential to eliminate the factor of extra cbst due to improvements in the vehicle and get down to a• difference brought about only because of the extra cost of the oil engine as compared with the petrol unit.
Here, on that basis, are three sets of figures, three prices. All relate to vehicles having double 'drop-sided bodies an long-wheelbase chassis. The price of vehicle make ''D is 2798 with an oil engine and £518 with a petrol engine. The price of a similar vehicle, make" E," is 21,123 with
an oil engine and £895 with a petrol unit. The corresponding figures for make "F " are £800 with an oil engine and £450 with a petrol unit.
The case of vehicle " F " is, however, a special one. The manufacturer is not, as yet, offering a complete vehicle with an oil engine incorporated. If an operator desires a chassis of that make with such a unit he must buy it with a petrol engine and then take steps ,to effect the change. That accounts for the somewhat enhanced difference in price-2350 as between the eller and the petrol-engined vehicle. To be fair, I think I should leave that example out of our calculation's and deal with only vehicles " and " E." .
Examining these, we find that the difference infirst cost varies from £228 to 2280 and if the mean of those two be taken we have, approximately, £250 as the differ-' ence in cost between an off-engined vehicle and one equipped with a petrol engine
Averaging the prices of the two vehicles " D " and " E,". we can take 2960 as being an average cost of an oiler and £710 as the average cost of a petrol vehicle. ,The difference between the two is £250 and this is due solely to the greater expense of the oil engine as compared
with the petrol unit. There is thus no need to make provision in our calculations for any difference in the quality of the vehicle itself, as apart from the engine.
Now, against this extra 2250 the user will endeavOur to set a saving in expenditure on fuel and the first question that arises is, what will that saving be?
Acparding to " The Commercial Motor " Tables of Operating Costs a 6-tonner consumes petrol at the rate of 9 m.p.g. That, as can be gathered from the explanatory remarks accompanying the Tables, is an average figure. A 6-ton oil-engined vehicle, quoted from the same source, is stated to consume fuel at the rate of 15i m.p.g.
Both figures are, I may say, fairly representative of the current experience of 'operators of this type of vehicle In adverse circumstances no doubt the consumption will increase: under favourable conditions better results may accrue.
jusf how much this difference means in pounds, shillings and pence and how far the saving offsets the cost of the oil-engined vehicle, cannot be stated without knowing, first of all, at what price the operator is buying his fuel. The Tables quote prices of 25. Id. and Is. 101d. per gallon Jr petrol and for oil fuel respectively. At those prices the comparaave costs per mile for fuel are petrol 2.73d. and oil fuel 1.44d. There is, therefore, a direct saving in fuel cost of no less than 1.34d. per mile.
How Lonk It Takes to Eliminate the Extra Cost Now, if we divide the extra cost, £250, by 1.3.4d., we can find how many miles the vehicle will have to run before the operator has made good the extra cost. That is shown to be 44,800 miles, or it is, probably, near enough to say 45,000 miles. In other words, if the operator be coveting anything over 22,500 miles per annum he will, according to the above calculation. wipe out the extra cost of the vehicle in less than a couple of years. Those who are in the fortunate position Of being able to buy their fuel in bulk pay less than the prices quoted, and that fact modifies the calculation, curiously enough, to the disadvantage of the oiler. The price of petrol has been quoted to me at Is. 11d, per gallon by such operators, whilst users of the oiler pay only Is. 8-id. for their fuel. At that rate the cost of petrol per mile is 2.56d. and that of oil file! 1.32d. The saving is, thus, 1.24d. per mile and on the extra cost of 2250 it is necessary to cover. 48,000 miles before the operator has recouped himself for the extra initial outlay.
The fuel prices staled above are maximum and minimum, so far as. the majority of users is concerned; so that it is fair to state that, in most cases, the difference in cost will
have been made up in from 45,000 to 48,000 miles. .
Many,operators will be satisfied with the above statement and calculation and will be inclined to inquire no farther. Nevertheless, confining myself for the moment to the interest of those who are so satisfied, I might point out that it isworth while to pursue the Subject' another stage.
Assume—as is certainly not true as a general rale—that' the oil engine and the petrol unit have the same life and that the lorry with which we are concerned runs for 150,000 miles before the owner decides that it is necessary. to replace it. The fuel cost, in the case of the .petrol vehicle, will lie between 150,000 times 2.56d. and 150,000 times 2.78d. That is, somewhere between £1,600 and £1,738 10s: The cost of oil fuel similarly calculated will lie between £825 and £900, so that there will be a saving in fuel cost, during the life of the vehicle, ranging from £775 to £838 10s., according to whether the operator is able to buy his fuel at the lower level or at the higher rate. The dearer the fuel the greater the saving—a fact which the owner-driver, who buys fuel at the retail price, should have well in mind when he is considering this problem: • As I have already stated, there are many readers who will be quite satisfied with the above rough-and-ready assessment of the saving. There is a possibility; they will argue; of saving up to three or three-and-a-half times the difference in the first. cost of the two types of vehicle, so why worry any more? Actually, of course, the whole story is not told in that simple and easy comparison; much more is needed if a true picture is to be shown.
Examining Vehicle Operating Costs
In order to get at the facts, it is necessary to examine the whole series of_operating costs of a Vehicle to see how they are affected by this difference in price. It is necessary to go. through the whole 10 items, i.e.: STANDING CHARGES: Licences, wages, rent and rates, insurance, interest on capital outlay; RUNNING COSTS: Fuel, lubricants, tyres, • maintenance and depreciation. These must be set down for each type of vehicle and checked one against the'iether, in detail and in sum, before we shall really know how we stand.
Looking quickly through the list of standing charges it is fairly obvious that only the item " interest " is going ,to be affected. That is an amount corresponding to ,3 per cent on £250, which is approximately 3s. per week. Probably the amount is not Worth bothering about, except for the fact that-if we are going to make the investigation we might as well be thorough about it. Turning to running costs, we have first of all fuel and I have already shown that the difference there is likely to be anything from 1.24d/to 1.34d, per mile in favour of the oiler.
With regard to lubricants, the credit goes the other way .No one, even the most hot-headed advocate of the oiler, will fail out with me if I insist that the lubrication costs of the oil engine are greater than those of the petrol unit It is necessary to be more careful in selecting the lubricating oil and it is Usually more expensive. Moreover, the manufacturer's recornniendation for changing the oil Inuit be more closely followed in the case of an oiler.
I am agreeable to take the figures in " The Commercial Motor " Tables of Operating Costs as a basis for this, that is to say, 0.16d. per mile for the petrol-engine vehicle and 0.18d. for the oil-engined vehicle, a differende of 0.02d. against the latter..
Oiler Maintenance .a Controversial Point So far as tyres are concerned there is, of course, no difference as between one and the other. The next item is maintenance and here a stage is reached Where there may arise some controversy.
There is a considerable difference of opinion about the cost of maintenance of oil engines as compared with petrol units. There is, indeed. considerable difference in experience of the maintenance costs of the two types as betweenone operator and another. There are two aspects to be considered. First, the labour, which is mainly involved in routine maintenance operations, and, secondly, the cost of materials when parts have to be renewed.
The cost of labour is less, prcivided that the organization for maintenance be-sound. The cost of materials and spares is greater but is not called for so frequently if— and I must repeat myself—the organization for main
tenance be sound. • I have, however, insufficient space nOW to deal with this aspect of the matter and prOpose to do so in my next article S.T.R. (To be continued.) •