Johnson Service Bulletin SB-784 - OMC Type B Lubricant

Since the introduction of OMC Type 'B' lubricant various questions have arisen concerning 'why'. Because there appears to be considerable confusion on the current lubricant, we think it may be well to cover the subject at greater length and state the reasons we have had to package and specify our own product.

Packaging of gear lubricant is not at all new with Johnson Motors. We had always packaged a gear grease until the use of hypoid oil came into the picture in 1948. At that time hypoid oil was satisfactory for the then current gearcases.

Since 1948, however, two things have changed considerably...outboard engines and hypoid oils. Outboard engines have become more powerful, and the gearcase lubricant requirements more demanding because of higher loads placed on gear teeth and bearings as a result of higher developed power and torque. Loading stresses on anti-friction bearings in gearcases of large engines are particularly critical. These bearings must be made as small as possible to reduce the gearcase area exposed to water since this factor substantially affects speed on fast boats.

The other factor affecting all hypoid lubricants is the requirement imposed by automotive applications. As a result, and as nearly as we can determine, many of the automotive hypoids have been changed in composition during the last two years resulting in a new hypoid oil to meet the special requirements of the new automotive rear axles and differentials. Unfortunately, differentiation cannot be made between the old and new hypoids by a simple, visual inspection.

The trouble which can be encountered with the new, special hypoid oils came to our attention with the 75 H.P. engine. First prototypes of this engine performed entirely satisfactory using the older types of hypoid oils, but would fail quickly with certain of the newer types. Some new hypoids attack the surfaces of rollers and races of the anti-friction bearings, sometimes causing extremely premature failures. This does not, however, imply, and should not in anyway be interpreted to mean, that the new hypoid oils are unsatisfactory for other types of applications. It means only that some of them are presently unacceptable for our specific requirements in providing optimum gear- case performance of outboard engines.

BECAUSE OF THE FOREGOING REASONS, OMC TYPE 'B' LUBRICANT IS THE ONLY LUBRICANT WE CAN AT THIS TIME CONFIDENTLY RECOMMEND FOR GEARCASES OF ALL JOHNSON ENGINES FOR WHICH HYPOID OILS WERE PREVIOUSLY SPECIFIED, INCLUDING AND PRECEDING 1960 MODELS. The present recommendation of using hypoid oil in 1960 engines of 18 H.P. or below was made to enable the dealer to use up his hypoid stock on hand. OMC Type 'B' will be recommended in all models of 1961 engines.

The Type 'B' lubricant now being packaged and specified is a lubricant that has been thoroughly tested and is completely satisfactory for our requirements. Even so, engineering continues to conduct tests in an attempt to find improved lubricants which will result in improved gearcase performance and longevity. Changes in OMC Type 'B' will be made only after thorough testing has been made, and provided such change constitutes an improvement.

An approved change was recently made in OMC Type 'B' which also affected color, and which is currently being used in production engines. Color of this changed lubricant is now black while the former Type 'B' was reddish in color. Such color differences do not, however, obsolete earlier OMC Type 'B' lubricants, thus permitting the earlier lubricant to be used for servicing purposes as required. Neither does color offer any indication as to the quality of the lubricant since quality is determined solely by the results obtained in testing.

We have received information that some dealers, on checking new engines before delivery, have noted the black lubricant and, thinking a mistake was made at the factory, drained and refilled the gearcase with red OMC Type 'B' from their own stock. Checking new engines prior to delivery is, of course, encouraged; but changing gearcase lubricant in new engines because of color differences is not necessary. The production department will generally be the first to use any changed lubricant as it is introduced. By all means, continue to use your stock of OMC Type 'B' regardless of color or color differences.