I would just go to an oil that has NO FRICTION MODIFIERS and is NOT synthetic. You do NOT need to go from full synth to partial to dyno! I use the "modern" GTX with no problems in the MNS, and I was running a 15W40 in the '79 with no problems until Chevron went to friction modifiers in the Delo.
As Steve said, the synthetic WILL seep out of seals! This is because of the makeup of the oil.
As Steve said, the synthetic WILL seep out of seals! This is because of the makeup of the oil.
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