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GENE, Auto Service Technician
Category: Car
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Difference between hypoid gear oil and synthetic oil?

Customer Question

What is the difference between hypoid gear oil and regular or synthetic oil? My 2006 Toyota Tacoma has a limited slip differential in the rear axle. The owner's manual calls for a 75w-90 hypoid gear oil. Is a full synthetic 75-90 oil okay to use?

Submitted: 9 years ago.
Category: Car
Expert:  GENE replied 9 years ago.

Yes, it is - this is an easy conversion - just drain and refill with the synthetic. Also, you can do all of the drive train with synthetic. I convert all of my cars and trucks with synthetic, it's a far better lube and oil, plus you will get better fuel mileage. It's slight, but it does give you an increase in mileage. I hope this helps, just make sure you get the correct weight gear oil and don't forget the trans too.

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Hypoid gear oil explained

What is hypoid gear oil?

Hypoid is used to describe the structure of gears instead of oil. The “hypoid” design on gears are shaped like two Christmas trees with mesh on each side at a 90-degree angle. This type of gear helps reduce noise and give a better rotation pressure for driving. This design has proven to be successful for cars that had the conventional manual transmission design. Since a lot of pressure is on the gears, a special lube is needed to protect them. This oil prevents gears from tearing up when under higher pressure.

Why is hypoid gear oil used?

Hypoid gear oil has additives added to help prevent parts from breaking down from high temperatures and powered pressure from the hypoid gearboxes.

Many different vehicles use gearbox oil. This type of oil provides lube for wheel axles, transmissions and other parts of the car. The thickness of gear oil is higher than standard engine oil, so the gears do not rub together. However, within time, by not cleaning the gears, old oil can turn into a dirt consistency and cause the gears to slow down. When the gears begin to slow down, this affects the performance of the vehicle.