I have one of the older R9's and when I bought it, the official policy was to use grease for lube. In reading all of the relevant threads, I gathered that the machining tolerances have been relaxed for the newer R9's and now the new official policy is any quality gun oil is acceptable. Is that a retroactive policy or should I still be using grease on my older R9? I haven't seen this question asked so I thought I'd ask it before switching to oil. Thanks for your help!