I an earlier post I wrote, I asked about Shell Helix Ultra and was told that it was one of the best oil's on the market. My 2013 SL 350 which I've owned for about 2 1/2 years with 42k on the clock has always had MB 229.5 oil used when serviced. In my ownership I've bought it from MB in Edinburgh, as they seem to be the cheapest and free delivery. However I don't use the car all that much and it lives in my garage out of the elements. but on start up after say 3/4 weeks I used to get a very slight and I mean slight rattle for about a second or so, the same when starting after about 1/2 hour after a run. I did a lot of research on this and was swayed into thinking I needed new secondary timing chain tensioners and the fitment of oil check valves which I would of undertaken myself. However since using the above mentioned oil the engine is silent both on cold start and hot start. As a time served mechanic (now retired) I'm slightly puzzled as to why this should be so, but there it is. So I shall continue using said oil and go down the road of ignorance is bliss.
I would be very interested to hear other members thoughts on this strange but true matter.
