Your mechanic is correct. Thin oil will cause noise since it is not able to prevent metal to metal contact.
WHAT STOPPED THE LIFTER NOISE 2011 DODGE GRAND CARAVAN
Over a year ago, I had to get one of the heads opened in order to replace #3 and #5 rocker arms. Well about 6 months ago, I started having the ticking noise again. I put up with it for a month or so,
I found a video on Youtube that was talking about using Marvel Mystery Oil and although I have added it oil before in small amounts, I had never used as much as a quart. Mostly, I put it in the fuel tank. This time instead of using 6 quarts of synthetic oil, I used 5 quarts and used 1 quart of Marvel Mystery Oil. After about 3 days the noise stopped and has not come back for over 3 months. Every oil change I started to do the same thing. At first I was using 5w30 and the last time to 5w20 but, I think i will go back to 5w30 because the Mystery Oil is real thin. BTW it smells really good also..
I found a video on Youtube that was talking about using Marvel Mystery Oil and although I have added it oil before in small amounts, I had never used as much as a quart. Mostly, I put it in the fuel tank. This time instead of using 6 quarts of synthetic oil, I used 5 quarts and used 1 quart of Marvel Mystery Oil. After about 3 days the noise stopped and has not come back for over 3 months. Every oil change I started to do the same thing. At first I was using 5w30 and the last time to 5w20 but, I think i will go back to 5w30 because the Mystery Oil is real thin. BTW it smells really good also..
