Meets or exceeds API CF-2 and provides an enhanced level of lubricant performance over the CD-II category for two-stroke cycle engines (Detroit Diesel Series 53, 71, 92, and 149). Single grade oils having less than 1% sulfated ash are preferred and primarily recommended for new Detroit Diesel design changes.

Sulfated ash is related to the oil's additive composition and is significant in predicting lubricants which may cause valve distress under certain operating conditions. Most of the sulfated ash is related to total base number which measures an oil's alkalinity and ability to neutralize acid. As TBN increases, sulfated ash also increases to where lubricants with a TBN above 10 will likely have sulfated ash contents above 1.0%.

It should be understood the use of PRO-SPEC^® D. D. MOTOR OIL is with fuel with less than 0.5% sulfur. For fuels with higher sulfur content, use PRO-SPEC^® SAE 40 with a TBN of 15. The higher TBN is necessary to offset the harmful effects of acids formed during the burning of high sulfur fuels.

High Total Base Numbers are important to control deposits in four-stroke cycle diesel engines and to neutralize the effects of high sulfur fuel in all diesel engines. For two-stroke cycle engines, Detroit Diesel recommends lubricants with a sulfated ash content of 1.0% or less and a TBN between 6 and 10 for engines operating on less than 0.5% sulfur fuel. Starting in 1994, diesel fuel for U.S. highway vehicles was limited to 0.05% sulfur content maximum. The need for high Total Base Numbers for over-the-road Detroit Diesel Engines ceases to be a problem in the U.S.A., providing the customer is buying fuel meeting these specifications. Of course, off highway diesel fuel may still have sulfur content much higher and that's where real care must be exercised in the recommendation of the proper engine oil.

If extreme cold weather (0 to -25°F.) prevents sufficient starter cranking speed with PRO-SPEC^® D. D. MOTOR OIL SAE 40, then the use of PRO-SPEC^® SAE 15W/40 or PRO-SPEC^® SAE 30 will improve start ability. These oils must be replaced with PRO-SPEC^® D. D. MOTOR OIL as soon as ambient conditions permit.

Exception: Do not use 15W/40 or SAE 30 lubricants in two-stroke cycle marine engines or series 149 engines under any circumstances.

It should be noted, PRO-SPEC^® D. D. MOTOR OIL is formulated in such a way that it will keep the engine cleaner than low ash commercial engine oils. The reason PRO-SPEC^® D. D. MOTOR OIL is better is because of excellent detergents and dispersants in a superior oil additive package plus highly refined base oils. The base oils have been refined in such a way to make the oil accept these superior quality additives - - - and the overall result is a cleaner engine.