cold weather break in

[kingsfisherman]

Hello,

I had my 98' 5.7 GSi rebuilt and I will be getting it back in the boat soon, but winter has started and I will be running it in temps above 0 degs-40's to break it in. What oil viscosity should I use? Manual says 20w/20 for temps 0-32 F and 30w for 32 degs and above.
Can't find any 20w/20 so now what?
TIA

 

[Pmt133]

20w-20 is an old spec. Later versions of the 5.7 call for 10w-30. I'd run that and not worry about it

 

[kingsfisherman]

20w-20 is an old spec. Later versions of the 5.7 call for 10w-30. I'd run that and not worry about it

would that be a good oil for the break-in period as well?

 

[Scott06]

would that be a good oil for the break-in period as well?

When I bought my new GM long block from Michigan motorz a few years back they insisted on rotella T4 conventional 15W40 for break in. Also wanted conventional oil for first 100 hrs before switching to synthetic

Your lower temps may play into it but I’d think you’d be fine using it. Long block I got is same as yours. A lot of guys run rotella in their boats.

I broke the engine in on a pallet then changed the oil after and hour or so. Changed it again after 10 hr break in then annually

 

[Scott Danforth]

install rotella T4 15w-40, put a bunch of hours on it to break it in, then change oil and put away for the winter.

 

[Chris1956]

When I had my MerCruiser, I wired a 40W heating pan under the oil pan. When temps were cold, I would plug the heating pad in several hours before use, to warm the oil. 40W was not enough to do anything but warm up the oil and help keep the manifolds from freezing.