10W-30 Oil All year?

[Rockymtnboy]

Hi All,

When I bought my 2008 Diesel, the dealership gave free oil changes for 2 years or 24,000 miles. Everytime I go in, they always put in Ford Motorcraft 10W-30, no matter what season it is. I asked last summer if they would put in 15W-40 and they told 10W30 is the recommended weight for year round use unless you are towing something heavy. I pointed out what the owner's said, and they said 15W-40 is good for towing, heavy, but 10W-30 was better for the motor overall.

Is this true? Is it really okay to run 10W-30 year round? Is this weight really better for this diesel enigine? I tow a 7,500 lb camper from time to time here in Colorado.

[ddduallyfan]

If your using that truck for anything other than getting groceries or running the kids to school you need to run 15-40 or better yet 5w-40 synthetic. But thats just me.

[surveyor13]

I would use whatever the manual says to use.

[SmokeyWren]

Originally Posted by Rockymtnboy

Is this true? Is it really okay to run 10W-30 year round?

No. It's okay to run 15w40 year 'round, but not 5w30. 5w30 is for freezing weather, or for gasoline engines. But not for diesels in the summertime. It's okay to use it in the spring and fall as long as ambient temps don't get up over 75º or 80º F. But it's a no no for summertime when ambient temps are constantly above 75º and often above 90º.

5w30 diesel-rated motor oil is extremely hard to find in the lower 48. Are you sure your dealer is using oil rated SJ-4/SL or better for your diesel? I somehow suspect they are putting "car" oil in your diesel engine.

[rlchv70]

Insist that they use 15w-40. If they refuse, tell them that you want a free 250k mile extended warranty. Any effects from running 10w-30 won't show itself right away.

[dirtyharry]

I ran into this with my dealer here in Canada. The reason for this is that all they were running in the 6.0L was 10W30 because the 6.0 ran like crap in the cold with 15W40. That is why in your owners manual it even shows 10W30 as recomended for the 6.0L's that they are still putting in the vans. However the 6.4L does not have this problem and runs fine on heavier oil since the fuel injection system is not affected by oil viscosity like the 6.0.
However most dealers near me only carry bulk 10W30 oil for the diesels and are resistant to switch over. So just insist on it and make them show you the oil. Make them use jug oil instead if they have to.
Go with what the owners manual states unless they have a bulletin from ford that states (in writing) different.
Also if they promised you free oil changes for 2 years make them change it every 8,000km since if you were paying for the oil changes they would tell you that is when to change it. Don't let them try and only do it every 16Km.

[justinthurn]

according to the diesel engine suppliment, 3rd printing, 10w30 is only good from 0 to 50 degrees f.

15w40 is not recommended below 20 degrees f.

below is a quote from the suppliment


An engine block heater must be used at temperatures below
–10°F (–23°C).

•

Use the same engine oil and filter change intervals when using
synthetic engine oil.

•

Heavier 15W–40 and 5W–40 engine oils are recommended for
temperature over 50°F (10°C) and must be used for heavy duty
driving and trailer towing.