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Why Use Engine Break-In Oil?

Engine building should go well if everything is done correctly. Once all the parts have been machined to the correct tolerances, assembled with the correct clearances and protected with the right kind of lubricant. Or, it can end disastrously if parts are too tight or too loose, if there’s not enough lubrication when the engine is first started, or if the motor oil being used during the break-in process fails to protect the cam and lifters or doesn’t allow the rings to seat. A lot of things can go wrong during those first few minutes following the initial start-up of a freshly built engine. The engine has to build oil pressure quickly so all of the critical wear surfaces will receive lubrication. Assembly lube is designed to cling to surfaces better than ordinary motor oil so there will be a protective film of lubricant until the engine is cranked over and started. From that point on, oil pressure should take over and flush away most of the assembly lube. That’s why priming the oil system prior to starting it is so important. Priming prevents a dry start and reduces the lag time for oil to reach the bearings, cam and upper valve train components.

Ordinary motor oil can be used to lightly lubricate cylinder walls, lifter bores, wrist pins, piston rings, timing chains and bearing surfaces. But if the engine sits for more than a few days, much of the protective oil film will trickle back into the crankcase. Adding a viscosity improver such as STP to ordinary SAE 30 motor oil will help it cling to critical surfaces longer, and adding a dose of extreme pressure additive such as zinc dialkyl dithiophosphate (ZDDP) or zinc-moly will provide additional protection for the cam lobes and lifters if the engine has a fl at tappet cam.

Engine builders around the world have grown increasingly concerned that many modern motor oils do not provide adequate wear protection for new engines, particularly those using fl at-tappet cams. Royal Purple has addressed this issue by developing a engine break-in oil. Royal Purple Break-in Oil is formulated to allow optimal ring seal and protect rotating assembly components, such as the camshaft and valve train, from initial start up wear. Royal Purple combines highly refined mineral oil, preferred for engine break-in, with advanced additives containing high levels of zinc and phosphorus to optimize protection in flat-tappet and roller engines. Royal Purple Break-in Oil is a fully formulated conventional 10W- 30 engine oil and does not require the use of any other chemical additives. Royal Purple recommends using their high performance synthetic motor oils after engine break-in for maximum engine performance and protection.

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