clavel... synthetic n mineral based engine oil have the same chemical components.. the diff is synthetic lasts longer n has more additives rather than mineral base.

walang kinalaman ang gasket leaks mo sa engine oil. the best thing to do is change the leaking gaskets.

san ba leaks mo valve cover? cyl head? intake or exhaust valve gasket?

one more what grade of oil u using? baka sobrang nipis ang gamit mo