2008-2010 Ford 6.4L Powerstroke Engine Oil

Engine oil on the 2008-2010 Ford 6.4L Powerstroke

The 6.4L holds 15.0 quarts with the filter, and Ford's spec is API CJ-4. The viscosity chart lists 15W-40 above 20 F, 10W-30 from 0 to 50 F, and 5W-40 above -20 F. Ford's published B50 service life for this engine was 375,000 miles, while Diesel World has called the 6.4L a 150,000-mile proposition. Oil dilution is the thread that ties most 6.4L engine failures together. That is why oil care on a 6.4L is a weekly habit, not a once-a-season chore.

What thins the oil and what it hurts

Fuel gets into the crankcase two ways. The factory DPF regeneration injects fuel late in the stroke so it burns in the DOC and DPF, and some of that fuel washes past the rings. Leaking piezo injector bodies can drain fuel into the crankcase too. Thin oil is hardest on the valvetrain. The rocker arms get their only oil through the pushrods, so fuel-diluted oil chews up rocker tips and bridge balls. Updated pushrods with larger oil holes and good CJ-4 oil are cited as the fix for rocker lubrication complaints. The routine that keeps you ahead of dilution: check the dipstick weekly, change the oil every 5,000 miles, and change it right away if the level climbs above max.

Choosing a grade and a brand

Start with the API rating and the viscosity chart, then pick the brand you trust. Ford called for CJ-4. Most of the oils on this page carry a CK-4 label, and the Lucas Magnum High TBN oil is labeled CI-4, so read the API symbol on the back of the jug and match it to what your owner's manual calls for. Full synthetic, synthetic blend and standard heavy-duty 15W-40 are all here; whichever you choose, make sure the grade is on the 6.4L chart. Lighter grades like 0W-20 and 5W-20 are not on that chart, so skip them for this engine.

What we carry

• Hot Shot's Secret Green Diamond full synthetic CK-4 in 15W-40, 10W-30 and 5W-40, Green Diamond 15W-40 semi-synthetic, Blue Diamond 5W-40 full synthetic, Black Diamond Outlaw 15W-40 and 10W-30, and ADRENALINE R-Series racing oils.
• Hot Shot's Secret TBN Booster oil stabilizer, FR3 Friction Reducer and The Original Stiction Eliminator.
• Lucas Oil 15W-40 CK-4, Synthetic 15W-40 CK-4, Synthetic Blend 10W-30 CK-4 and Magnum High TBN 15W-40 engine oils, plus Heavy Duty and Synthetic Heavy Duty oil stabilizers and TB Zinc Plus break-in additive.
• XDP X-Factor high performance oil additive.

Additives are optional, and none of them replace a 5,000-mile change on a 6.4L. The rest of our 6.4L engine parts live under Powerstroke.

Fitment notes

Oil fits by spec, not by part number. Use the 6.4L's own numbers: 15.0 quarts with the filter, API CJ-4, and the viscosity chart above. Four 1-gallon jugs cover a change with a little left over for top-off. The 6.4L is unique to 2008-2010 and shares no long-block parts with the 6.0L or 6.7L, so go by its own numbers rather than another Powerstroke's.

Frequently asked questions

What oil weight should I run in a 6.4L Powerstroke?

Go by temperature. The chart lists 15W-40 above 20 F, 10W-30 from 0 to 50 F, and 5W-40 above -20 F. A truck that lives in Florida heat sits squarely in 15W-40 territory. If your truck sees mornings below 0 F, 5W-40 is the grade on the chart that covers it.

How often should I change the oil in a 6.4L?

Every 5,000 miles. Ford's normal interval was 10,000 miles or six months, with 5,000 for severe service, but the shop consensus on this engine is 5,000 because of fuel dilution. Check the dipstick weekly in between.

Why is the oil level on my 6.4L going up?

Fuel is getting into the crankcase. On this engine it can come from DPF regeneration or from a leaking piezo injector body. Change the oil right away when the level exceeds max, and if it keeps rising, have the injectors looked at.

What does milky oil mean on a 6.4L?

Milky oil means coolant, not fuel, is in the crankcase. One known cause on the 6.4L is the aluminum front cover eroding from cavitation behind the water pump on trucks run low on coolant, though Fleet Service NW calls it uncommon. Don't keep driving it; get it diagnosed.

Not sure what fits? Call the shop at the number in the header, or use the fitment checker on any product page. We install everything we sell.