Will thinner oil reduce cold start rattle?
 

2000 2.7, 115k. I've had this car for a few weeks now and it has a slight rattle, for less than a second, when started cold. It sounds like lifter noise to me. When I inspected the car prepurchase, I made sure to start it up with the engine dead cold, and I don't remember hearing anything.

As soon as I got the car home, the first thing I did was change the oil to Mobil 1 15-50, car had M1 0-40 in it when I bought it.

So my question is, will the thicker oil make the car more likely to rattle on a cold startup and should I switch back to 0-40?

When I switched to 15W-50 last year, my first start out of hibernation went ok but after it warmed, I had the ticking associated with a flat lifter.

I've changed to Syntec 10W40 and have not noise at all either at start up of after on the road for an hour. I have to say that using Syntec has seems to have gotten rid of all the ticking or metallic noises coming from the engine.

+1 on the Syntec. I just changed from M1 0w40 to Syntec 5w40 yesterday and I am amazed by the reduction in mechanical noise, especially at start-up. The motor seems to run much smoother.

Why 15-50, btw?

A lot of people think that heavier is better in terms of oil weights, and that it will offer more protection, but the thing that you have to keep in mind, is that during a good part of an engine's life, the oil is not at operating temp, and this is the area that you really want to choose the lesser of evils in.

Also, while we certainly need oil pressure, more is not necessarily better, while more oil flow is always better.

There is a great article on Ferrari chat that I have linked below. If you'd like to kill a few hours reading this, this is some excellent information in it.

http://www.ferrarichat.com/forum/faq.php?faq=haas_articles

Cold start rattle is due to clogged or dirty chain tensioners.. If you have that syndrome, clean or replace the tensioners.

Can they be replaced fairly easily, as in not having to take off the cam covers and locking the cam timing?

Since you have a 5 chain motor, you don't HAVE to lock the cams, but it's not the worst idea. It is ABSOLUTELY critical, however, that you put the engine at TDC before you even think of pulling a tensioner.

Should I pull the cam caps and mark the cam position so I can make sure the timimg doesn't change? Is so, do i need to mark the cams on both sides or is one side OK?

Personally, I would stick to the M1 0-40 for everyday driving.

If you aren't going to lock them both, you could just pop the caps on the passenger side (whose chain is at the back of the car, right next to where the IMS is driven by the crank) and verify that things haven't shifted. As long as you put the engine at TDC and don't turn the crank with the tensioners out, you should be just fine.

I used to use M1 0W40. After switching to Motul 10W40 alot of the startup rattles and other noises were greatly reduced.