Silver85TC said:
If a gasket is drying out and isn't sealing quite as well as it did when new, the combination of cleaning the crud and the improved flow properties of the synthetic oil WILL create a leak where there was none before. Calling synthetic oil "thinner" is a misnomer. Synthetic oil does flow better, but its "weight" is the same as an equivilant dino oil. 10-30 oil is 10-30 oil, regardless if its dino or synthetic.
i respectfully have disagree with a point or two.
ya might want to double check on the 'thinness' part. it is referred to as being a 'thin XXX weight' and synthetics can do it because of their normally (AND people not all synthetics are) man-made nature. one popular oil comes to mind - their cold 15 weight is more congruitious to a 10 weight.
viscosity is based on how an oil performs at 0/100*C, pour points, etc - it has nothing to do with the physical thickness (though it generally is close for a given weight of oil). weights of oils are based on characteristics and requirements, not physical viscosity.
synthetics can be made thinner to flow better cold, while still being able to withstand higher stresses when hot (due to the synthetic properties, be it a GIII, IV, or V). some brands of synthetics or even different applications see oils which are on different sides of the spectrum (i.e. the heavier racing oils [road racing, etc] tend to be a heavy oil because it is assumed the car will see the most extreme of extreme). a DD in Michigan winter does not need the high temp stability but does need good flow at lower temps (shift in the operating conditions and thus different proportions/properties in the blend).
also, i know what you meant above, but i think it was phrased ambiguously. synthetic oil seldom "creates" leaks, as was posted. it does 'enlighten' you to their whereabouts. i think choosing the use of the word "create" was poor. if i go hiking and fall and my wounds are covered in dirt, then i go home and take a shower, the water that reveals my cuts did not create them. it only showed me them.
i would have said 'unmask' or something along that line - i know i'm nitpicking semantics but syn oil creating leaks is a huge misnomer and i hate for someone to get the wrong impression if not reading carefully (like me.

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with much of the synthetic stuff, there is no one answer; it is application specific. to that end, i say run whatever floats your boat.
