I've got a 2008 Cadillac with the Northstar V8 and about 150k on the odometer. Most everything is in good condition on the car and I'd like to keep driving it.

It's been increasingly leaking oil over the last two years, which I understand is very common for these engines, but the headgasket is fine and my mechanic says it's in the best condition that can be expected - it's just doing what Northstars do, and I'm lucky it's only the oil on the driveway that's wrong with it.

What type of oil should I be putting in this thing, and how often should I be changing it? I'm currently putting between 3 to 5k miles per year on the vehicle It gets driven maybe 3x per week for shopping trips and about once a month for out of town for trips to Houston, Austin, or Dallas (from BCS).

Also, any other recommendations for how to treat a high mileage Northstar (other than selling it)?

How much oil is it leaking?

If it's >1qt a month, I'd just replace the filter every 3-4 months and keep topping it off with whatever oil Cadillac calls for. Don't put any "leak stop" product in it. All that crud is snake oil.

Just topping it off will let you run it until it dies of something bigger than an oil leak. It doesn't sound like you want to keep it forever, so I wouldn't put too much money into it....

if you want to increase longevity why not fix the leaks?

sts7049 said:

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if you want to increase longevity why not fix the leaks?

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A proper reseal of the ones leaking would run about half the value of the entire car. A full reseal would run about 75% of the value of the car.

Tim Weaver said:

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How much oil is it leaking?

If it's >1qt a month, I'd just replace the filter every 3-4 months and keep topping it off with whatever oil Cadillac calls for. Don't put any "leak stop" product in it. All that crud is snake oil.

Just topping it off will let you run it until it dies of something bigger than an oil leak. It doesn't sound like you want to keep it forever, so I wouldn't put too much money into it....

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Much less than one quart per month. Probably one-third of a quart per month at most. Over two years I've gotten quite the spot on the driveway though.

The car was a gift from a relative and suits my limited travel needs with occasional highway trips well. Everything still works very well on the car. But I'm realistic about the lifespan of Northstar engines with the headgasket issues and costly repairs of oil leaks once they get too bad.

I would sell it for market value and just buy something new, but the relative who gave me the car would likely not appreciate me doing that. So I've got a $3500 vehicle that I don't want to put $2k in for repairs but want to keep on the road a few more years.

The recommended oil is Mobil 1 5W20, would switching to a different viscosity or type improve leakage from the seals?

Maybe switch to the high mileage formula from Mobil 1, I wouldn't jack with the viscosity. Its not going to fix your leak but maybe slow it down...

Where are the leaks coming from? Top? Bottom?

There has to be a leak somewhere if its dripping.

Cannew said:

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Maybe switch to the high mileage formula from Mobil 1, I wouldn't jack with the viscosity. Its not going to fix your leak but maybe slow it down...

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Maybe switch to the high mileage formula from Mobil 1, I wouldn't jack with the viscosity. Its not going to fix your leak but maybe slow it down...

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This.

An oil leak will *probably* not hurt the car. The high mileage oil might help stem the tide of the leak a little, but unlikely.

In our area it's OK to go up on the viscosity a little too. Maybe try a 10w-xx oil and see if it helps. The 5w number is there for cold climates. Idk about you, but these 100 degree temps don't say cold climate to me...


Back in the old days, race teams would save money by changing the filter on a car instead of a full oil change. Put a new filter on and top off the oil and keep running it. Oil lasts a lot longer than you would expect, but the filters get full of junk. That's what you need to pay attention too.

As long as your filter is changed every 3-4 months and the oil does a complete change out every 2 filters, I think this car will be fine until the motor spits out its head gaskets. Just use it until then.

For your driveway, just live with it. You can throw a bunch of kitty litter there and replace it after the rain washes it away I guess.







Lol, I guess you could always drain the coolant and drive it around until it overheats, then your relative shouldn't mind when you junk it!

High mileage oil stopped a similar leak on a high mileage Yukon Denali for me a few years ago.

SparkE said:

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sts7049 said:

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if you want to increase longevity why not fix the leaks?

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A proper reseal of the ones leaking would run about half the value of the entire car. A full reseal would run about 75% of the value of the car.

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Well yeah, 10 yr old cars aren't worth a whole pile. Fixing is cheaper than buying new, right?

Sounds like a good excuse to get dirty at home and learn some stuff. DIY

beefiedoubleoh said:

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SparkE said:

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sts7049 said:

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if you want to increase longevity why not fix the leaks?

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A proper reseal of the ones leaking would run about half the value of the entire car. A full reseal would run about 75% of the value of the car.

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Well yeah, 10 yr old cars aren't worth a whole pile. Fixing is cheaper than buying new, right?

Sounds like a good excuse to get dirty at home and learn some stuff. DIY

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I still wouldn't even try. The Northstar motors are not known for their longevity. Also, 08 Cadillac. Meh.