I have a yanmar ex2900 that currently has wolfs head ht in it from the dealer. It's hydrostatic. The dipstick is telling me to add fluid. I can't find it by the quart anywhere. Is it ok to add a quart or so of something else like the traveller premium fluid or do I really need to buy another 5gal pail of the ht? I currently have the traveller here so that's the preferred option. How much cushion is built into these dipsticks? A mechanic at the dealership indicated I would most likely be ok to leave it at the current level. Thx