Tales From The Tech Line: Keeping Gears Cool During Break-in
August 11, 2021 - 10:18 AM -
Tech Question:
I just installed your Yukon limited slip carrier and 3.42 ring and pinion in my GM 10 bolt. I’ve been breaking it in correctly. It’s been about 120 miles so far and it’s still hot to the touch. I can keep my hand on it for about a second or two. When will this thing start running cooler and when would you recommend my first oil change? Thanks.
Tech Visitor, RANDYS Worldwide Website
Tech Answer:
Hot to touch is a poor form of measurement… most people struggle to hold a cup of coffee that is 140°, a shower at 120° will scald you. The normal operating temp of a differential is 175° to 250° depending on the type of driving you’re doing. We recommend using a handheld infrared digital thermometer which cost $15 to $50 to get a more accurate temperature reading. Use your findings in the chart below to determine your oil change interval.
Temp Reference / Oil Change Frequency Chart
Temperature Frequency
170° 100,000 Miles
200° 50,000 Miles
220° 25,000 Miles
240° 12,000 Miles
260° 5,000 Miles
260°-300° 500-1,000 Miles until temp is controlled
Running 250° to 275° is normal for new differentials during the break-in period. It is critical to not tow or take long road trips for first 500 miles as this builds additional heat. At 300° the diff is considered too hot and it should be allowed to cool. Once broken in, the normal operating temperature for a differential for vehicle in stock trim and regular diving is 170° to 220°. Normal operating temperature on vehicles with large tires, undersized differentials, or while towing is 200° to 250°. Remember, a new gear break-in requires an oil change at 500 miles.
Gus Pyeatt, RANDYS Worldwide Tech Support
For more info on gear oil and additives check out this article.
For more info on gear set break-in procedure check out this video.
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