Lubes & Greases FAQ

Q. From where can I get SERVO Lubricants for my car?

Ans: For your individual lubricant requirements or for your own consumption SERVO is available at your nearest IndianOil Petrol Pumps or Bazaar shops, spare parts shops etc. All such resellers are supplied lubricants from area specific sole SERVO Automotive STOCKISTs.

Q. Can I pay by credit card?

Ans: No, fuel is not supplied on credit cards. However, IndianOil issues a prepaid card for domestic operators only (called Carnet Card) on application.

Q. How can I purchase SERVO lubricants for my industry?

Ans: IndianOil supplies lubricants directly to customers whose requirement is above 30,000 liters per annum. If the requirements are below 30,000 liters per annum, then IndianOil services it through authorized sole SERVO Industrial Stockists specific for that area. However all institutional customers will get due customized solutions and dedicated customer service from IndianOil.

Q. When I use SERVO engine oil of IndianOil in my vehicle engine, after some time the engine oil starts turning dark and does not retain original colour. My mechanic says good quality engine oil should not start becoming darker and retain the original colour throughout. Can you please comment since his explanation seems logical at the outset.

Ans: Thanks for seeking clarifications. Every lubricant has to do basic function of eliminating / minimizing solid friction & mechanical wear and tear. But expectation from engine oil as lubricant is very much beyond this, it has to act as coolant removing the heat, sealant to avoid blowby, protect from chemical corrosive wear and also act as cleaner to keep the engine parts perfectly clean to enable the engine to perform at the highest possible efficiency. However good the engine may be, some soot / deposits are bound to form due to incomplete burning of some portion of fuel. This will tend to form black deposit on the engine part. Engine oil has to ensure that the deposit does not form/remain on the engine part. It sweeps the deposit and keeps the engine clean. Engine oil divides the deposit in miconic sized particle size so that the deposit does not settle down in the oil ducts. These properties are imparted by detergent dispersant additives.

Therefore if any engine oil gets darker during service, it means it is very good engine oil doing it's job perfectly in respect of cleaning the engine parts. Engine oil which does not turn dark, does not get dirty and retains original colour throughout is actually a very bad oil, not cleaning the engine and thus actually harming the engine. However if the engine oil starts getting dirtier and darker very rapidly with lumps of deposits in it, then it means either the engine condition is extremely bad or lubricant is of inferior quality and by itself generates deposits. This aspect can be cross checked. This will be the case if engine oil is purchased from non reliable sources.

Q. Earlier I was using mono grade engine oil in my vehicle. A friend of mine told me to use multigrade engine oil to get better mileage for diesel. But I find with the use of multigrade engine oil, pressure gauge shows lower pressure than what it was with mono grade. My mechanic says this can damage the engine and that I should at once switch back to monograde engine oil to protect my engine.

Ans: The pressure you observe in oil pressure throughout is on account of resistance offered by the oil ducts, filters, bends, orifices etc in the oil flow system in the process of reaching adequate quantity of engine oil to all the parts to be lubricated. The oil pressure required between the rubbing metal surfaces to avoid physical contact of the metal surfaces may be more than 100 times the pressure observed on the pressure gauge. This very high pressure is created automatically by the physical movement of the parts like rotating shaft, sliding piston rings etc and by the viscosity of the lubricant by what is known in tribology (science of rubbing surfaces including lubrication science) as elasto hydro dynamic lubrication regime. Engine oil has to lubricate some engine parts at very high temperature, beyond 1000C. Viscosity of lubricant changes very much with temperature. This could be 12 to 15 times or so between 400C and 1000C. For example viscosity may be 180cSt at 400C and say 15.5 cSt at 1000C.

This behavior can be changed by better refining (more Paraffinic oil means higher viscosity index which means lesser temperature variation) and by using viscosity index improver. In this fashion oil of low viscosity is selected so that viscosity at lower temperature is significantly low and by using the Viscosity Index Additive, the viscosity at 1000C is raised artificially. This ensures requisite viscosity at higher temperatures but relatively lower viscosity at lower temperatures. This means easy starting at lower temperatures, lesser undue viscous drag at lower temperatures and no compromise on quality of lubrication. Thus multigrade means making oil to meet two contrary viscosity requirements like viscosity requirement of SAE 20 W as well as viscosity requirement of SAE 40. Hence the oil may be known as SAE 20W40 or SAE 15W40 or SAE 10W40 or SAE 20W50 etc depending on which two viscosity grade requirements are met.

Therefore it becomes apparent that pressure required to make multigrade oil to flow through a duct for the same flow rate at temperature below 1000C will be less than the pressure required to make monograde oil to flow under same conditions. It is also pertinent to note that multigrade oil will have higher viscosity than monograde oil at temperature above 1000C, viscosity reduces as shear rate increases and hence assures better sealing, better lubrication, more power output and lesser lubricant consumption. Hence the said observation of lower pressure in the oil pressure gauge. This is just natural and desired. There is absolutely nothing to worry about.