Jon, On most large boats we purchased we wrote into the purchase agreement that all fluids would be sampled and examined by a competent lab. Now, before you go on to say that this is not an accurate test let me say this. Something is better then nothing. As long as results show normal I get that warm and fussy feeling about the purchase. On one twin diesel rig, that test showed an very high level of anti freeze in the oil. So the other guy paid for the head gasket job. As much money as one of these buses cost many purchasers won't spend any money on a survey. IMHO the RV industry has done a AAA job of keeping a pre-purchase survey out of coach buying.
AL
05 Marathon XL II (with shield)
010 GMC Acadia AWD