Just curious if a bypass filter would help this car. Its a 2008 BMW 750LI 4.8 LTR. It runs very hot and has a known issue of the valve seals drying and becoming hard , this allows the oil into the combustion chambers. To repair this problem can cost in the thousands so I am hoping to find a solution. Some have suggested running a lower temp thermostat ,that will make the motor run cooler but I've been told you sacrifice fuel millage which is something id rather avoid. I am seriously looking at a bypass filter as a means of 1) allowing the oil to be cooler. 2) the oil will be cleaner so the engine being an aluminum block will hopefully get more miles due to the cleaning effects of a bypass filter. 3) since a bypass adds an additional liter of oil , it would benefit the engine oil running cooler but would help not to cook the valve seals. 4) running the oil longer between changes. if this is all true what would be the best Bypass filtration system ?
bypass filter for BMW 2008 750LI
- Thread starter synman
- Start date
I’d just change your oil more often (4-6k) with a BMW spec oil. No need for a bypass.
You wouldn't get much cooling with a bypass filter, a frantz or similar setup would add 3/4 of a litre in oil capacity, if heat is the main issue why not add on a oil cooler?
I've considered a oil cooler , just not sure if that will allow for longer oil changes.
CleanSump
Site Donor 2026
A bypass filter won't help the valve stem seals.
BLUF - you bought a 7 Series BMW and there is no shortcut to maintaining it with timely oil changes with appropriate oil.
BLUF - you bought a 7 Series BMW and there is no shortcut to maintaining it with timely oil changes with appropriate oil.
+1 for the above comments about the filtration system helping temps.
Maybe look into running a higher-quality oil? I would look/reach out to the team at HPL (High Performance Lubricants) and see what they have to say. You can have your cake and eat it, too, with longer drain intervals given how you drive. Do you track it or just daily?
Amsoil, HPL would be my go-to for your situation.
Maybe look into running a higher-quality oil? I would look/reach out to the team at HPL (High Performance Lubricants) and see what they have to say. You can have your cake and eat it, too, with longer drain intervals given how you drive. Do you track it or just daily?
Amsoil, HPL would be my go-to for your situation.
The best you can do is use a "High Mileage" oil which will try to soften the already hard old seals. You want to use a 40 grade in order to maintain the minimum HTHS. An alternative is to use an oil additive like Liqui-Moly Oil Saver or AT-205. These products contain the similar seal swellers (ex, esters) found in High Mileage oils.
New seals will be made of a different material (Viton) and have a longer life but we're already talking a 25+ yr old car.
It appears that engine is already equipped with an oil cooler and holds 8 ltr of engine oil, there is very little you can do to reduce oil temps that has not been done OE. Do not try long OCI with euro cars, it is a recipe for disaster in the long run, use high quality synthetic oil and change it often. The ideal solution for the hardening valve seals is to use better seals.
I’d wager there are very few of these engines still on the road.
A 1-quart increase in capacity is negligible.
But generally speaking, a larger volume of oil doesn’t run cooler, it just takes a bit longer to heat-up…and also a bit longer to cool-down.
A 1-quart increase in capacity is negligible.
But generally speaking, a larger volume of oil doesn’t run cooler, it just takes a bit longer to heat-up…and also a bit longer to cool-down.
Doesn't the oil cooler make the oil just match the temperature of the coolant? Trying to reduce the temperature of the oil isn't going to change the temperature the engine is running if the coolant temps are high, which is the real cause of the seal issue. the hot coolant is just going to heat the oil back up to coolant temps anyway. The lower thermostat or better heat transfer are really the solution. This has little to do with oil.
You're driving a BMW 7-series with a V8, if you're pinching pennies on gas you might want to get a Corolla to daily drive man! The extra bonus is you'd be much more likely to make it where you're going without encountering a tow and a five-figure repair bill.
You should move to Canada where we live, we pay $8.31 a gallon , the car was actually quite affordable before the sudden rise in gas prices. Use to pay $100 to fill the tank , its now doubled. We pay the highest food prices in the G7 countries. its not penny pinching its all about survival. Be thank-full you live in the U.S. where taxes are lower and everything is very much affordable compared to our crummy socialist government.
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