I'm finally getting around to getting my RV-3B with its 13B flying again. Hasn't flown for 4 years or more.

I can turn the engine by hand but several of the apex seals are stuck -- won't move (back out) when pushing with a wood rod through leading sparkplug holes.

What's the best to spray in there to loosen them up/? WD-40?

I'm reluctant to use carb or brake cleaner -- might they degrade the rubber corner seals or maybe o-rings?

Finn