LOWER GRADE OF PETROL

Southland Times, Issue 24227, 10 September 1940, Page 6

LOWER GRADE OF PETROL

Efficiency Of Modern Cars Affected

LESS MILEAGE MAY BE EXPECTED

In conformity with a decision announced by the oil companies in Wellington on Saturday, that only one grade of petrol would be sold in future, resellers in Invercargill began the sale yesterday of a mixture of half-super and half-standard grade. The price charged is 2/BJ. Formerly standard petrol was sold at 2/7| and super at 2/BJ. When the stocks of super are exhausted and standard petrol only is ■on sale, the price will be reduced by Jd. Some resellers in Invercargill yesterday had stocks of super, but these 1 will soon be exhausted. As from yesterday, all garage proprietors and resellers are being required by the oil companies to pay cash for their supplies, whereas in the past a certain amount of credit was allowed. This decision affects resellers’ profits since in the past they have extended credit to motorists, and the position as it affects the trade will be reviewed at a meeting of the Southland branch of the New Zealand Garage Proprietors’ and Petrol Resellers’ Association which is to be held tonight. It is contemplated charging a booking fee.- , As modern cars, both English and American, are built for the consumption of super petrol, which is spirit that contains tetra-ethyl-lead, some inconvenience will be caused to motorists by the change-over to a half-and-half mixture, and greater inconvenience still when only the standard grade will be' on sale. ADJUSTMENTS NECESSARY

The change-over will mean that motorists will have to have the ignition of their cars readjusted by having the spark retarded, an operation best carried out by a skilled mechanic. Even when this adjustment is made, modern cars will give an inferior performance on standard petrol than with super spirit. Authorities in the trade in Invercargill estimated yesterday that the aver-aged-sized modern car would do from one to two fewer miles to the gallon on standard spirit, and assuming that the performance of a large proportion of the cars on the road will be thus adversely affected, it means that fewer miles can be travelled by motorists in New Zealand if the fixed petrol allowances now obtaining remain in force.

Modern cars operating solely on standard petrol may do a mileage a gallon up to 5 per cent, less than they have been doing on super petrol. The performances of older model cars will not be so adversely affected, since their carburettion and their compression ratios have not been set expressly to take super petrol, as with modern cars.

The advanced ignition which is possible on modern cars using “antiknock,” or super, petrol plays an important part in keeping petrol consumption at a minimum, and when the spark has to be retarded consumption will naturally increase. “The enforced use of standard petrol will lead to some uncomfortable motoring,” said one trade ( authority yesterday. If the spark on modern cars were retarded to the point where ignition “pinging” was eliminated, the probability was that pre-ignition or detonations through overheating would result.

It was said by one authority that the engine efficiency of cars with a compression ratio of more than six to one, a classification which includes moderncars, would be affected by the use of standard petrol, but that cars having a compression of under six to one would not be affected.