cold weather break in oil

Joined
Nov 8, 2025
Messages
6
Hello All,

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
 
This is a boat, not car. Very severe duty
Use sae 30. It will flow at any temp water is liquid. Let idle in gear for 5 minutes, then cruise at moderate load until oil is warm. 5 more min. Then break in per manual. Most stern drive oil is 20w40. It will work too.
 
Out of curiosity I did a quick Google search to your question. I don't think I have ever seen so many different suggestions and responses! I see everything from a straight 30 weight to 5W-30 to 10W-30 to a 5W-40 T6 to Mercruiser 25W-40 to a15w-50 but I see NOTHING in my search suggesting a 20W-20 as OP suggest is in the manual.

I know nothing about a boat inboard and could not even guess but my Google search turned up this ( link attached ) Boat engine break-in instructions that may include useful info from RPM Limits, including a warning to DO NOT start and allow engine to idle at 500 to 700 rpm and to idle at a minimum of 1,500 RPMs or engine DAMAGE can result...
Its a good read and may very well be helpful including proper oil to use...

LINK BELOW
https://michiganmotorz.com/content/MARINE ENGINE BREAK-IN 2024.pdf
 
Out of curiosity I did a quick Google search to your question. I don't think I have ever seen so many different suggestions and responses! I see everything from a straight 30 weight to 5W-30 to 10W-30 to a 5W-40 T6 to Mercruiser 25W-40 to a15w-50 but I see NOTHING in my search suggesting a 20W-20 as OP suggest is in the manual.
Here's the Operator's Manual. Page 43 is break-in and oil viscosities:
https://pubs.volvopenta.com/publications/7797286

It mentions all these viscosities, depending on the ambient temp:
32°F (0°C) – above: SAE 30, SAE 20W-50, SAE 15W-50
0°F (-18°C) – 32°F (0°C): SAE 20W-20
Below 0°F (-18°C): SAE 10W

This is page 44:
IMPORTANT
Failure to follow the break-in procedure may void the engine warranty.


First two hours

1. For the first five to ten minutes of operation, operate the engine at a fast idle (above 1500 RPM).

2. During the remaining first two hours of operation, accelerate to bring the boat onto plane quickly; bring the
throttle back to maintain a planing attitude.

During this period, vary the engine speed frequently by accelerating to approximately . throttle for two to three
minutes, then back to minimum cruising speed.

3. After the engine has reached operating temperature, momentarily reduce engine speed, then increase engine
speed, to assist break-in of rings and bearings. Maintain plane to avoid excessive engine load.


IMPORTANT
For this initial two hour break-in, do not run the engine at any constant RPM for prolonged periods of time.

Next eight hours

1. During the next eight hours, continue to operate at approximately . throttle or less (minimum cruising speed).

Occasionally reduce throttle to idle speed for a cooling period.

2. During this eight hours of operation you may operate at full throttle for periods of less than two minutes.


Final ten hours

1. During the final ten hours of break-in, you may operate at full throttle for five to ten minutes at a time.

2. After warming the engine to operating temperature, momentarily increase engine speed.

3. Occasionally reduce engine speed to idle to provide cooling periods.

At the end of the 20 hour break-in period, drain the engine oil and replace the oil filter. Fill the crankcase with Volvo
Penta’s DuraPlus™ premium engine oil labeled for Service CE/SG.
 
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