Is synthetic oil bad for old BMWs?

bmw oil, conventional vs synthetic

Is synthetic motor oil bad for old BMWs? Many older BMW models, such as the E30, were designed prior to the mass adoption of full synthetic or even synthetic blends. The standard rule of thumb when changing oils in vehicles is to use the same type of oil that was used when your engine was delivered from the factory. With all modern BMW engines using synthetic, the question arises: Is it safe to use synthetic oil in older model BMWs? The short answer is, yes. It is safe. Let us explain why below.

What exactly is synthetic oil?

Synthetic oils are man made, chemically engineered, to provide superior properties to that of crude oils which are drilled out of the ground and then refined. Synthetic motor oils were developed in 1929. The use of synthetic oils became essential during World War II after bombing of oil refineries and demand on crude oil. Further more, during the 1970s energy crisis in America and the western world the use of synthetics saw a high demand.

Why could there be an issue using synthetic motor oil in older BMws?

Early synthetic oils were ester based along with early engine seals. This combination often became an issue when in contact with each other. The ester based seals swell up when in contact with ester based oils. Issues that may arise are overswelling of the seal, cracking and loss of elasticity. Over time, the engine seals would break down quicker and result in oil leaks.

Can I use synthetic oil in my older BMW?

Modern synthetics have addressed the issues with the rubber seal compatibility of older engines. Chemical engineering and oil development has come a long way since the 1970s. If you decide to use a synthetic oil in an older model BMW, oil makers recommend you still stick with the recommended oil viscosity. This will ensure proper oil flow between the originally designed clearances of moving parts.

What are the advantages?

➊ Longer oil change intervals due to the oil taking longer to break down.
➋ Less oil sludge accumulation due to less impurities.
➌ Better viscosity properties for cold and hot weather climates.
➍ Better properties for turbochargers to lubricate smaller components.

Quick Links:

➊ Motor Oil Basics, Viscosity and Weights explained.
➋ How to reset E30 oil service inspection light.
➌ How to reset E36 oil service inspection light.
➍ How to reset E46 oil service inspection light.
➎ How to reset E39, E38, E53 X5 oil service inspection light.

Shop Now

BMW Oil Ratings Explained