Would you change your oil now or wait?

[xil]

Currently running Quaker State Ultimate 5w30 in my Mitsubishi 4b11T engine. 90% highway 80-90 mph, 10% stuck in stop and go traffic.

I normally run QSUD 5w30 with a FRAM Ultra filter on a 4500-5000 mi OCI and never had a problem.

I was 150 miles out of state and trying to make it back home at decent hour (before 2am). I was booking it. The motor was at 4500-5000 rpm for over an hour straight on the interstate, I'm sure the turbo was glowing red hot the whole time.

The oil has about 2800 miles on it. Would you change it now or just wait it out?

EDIT: Also, the engine has 100,300 miles on it and it sits at around 3000rpm cruising on the highway for most of its life. About 20% of the highway time is actually at 45-50mph cruising at 2200rpm. I do beat on it on the backcountry winding roads once or twice a week or from a standstill in the city, mostly to get away from idiots on the road. So far it doesn't burn a single drop of oil.

 

[4wheeldog]

That treatment is actually easier on the oil than stop and slow traffic. I would not worry about changing it before you normally do.

 

[donnyj08]

Originally Posted By: 4wheeldog
That treatment is actually easier on the oil than stop and slow traffic. I would not worry about changing it before you normally do.


^ what he said.

 

[CarbonSteel]

I would wait; QSUD is a synthetic oil and highway miles (unless towing) are fairly easy on oil. Hopefully, you allowed the turbo to spin down for a few minutes and did not simply shut it off after the run.

 

[BikeWhisperer]

^^^

Cooling down the tubro would be the key, other than that I don't see any reason to change the oil earlier than you already do.

 

[xil]

Originally Posted By: 4wheeldog
That treatment is actually easier on the oil than stop and slow traffic. I would not worry about changing it before you normally do.


I understand that highway driving is better but I always read on this site (on various posts) that the turbos beat up oil like crazy and I wasn't so sure keeping it at near 5k rpm for over an hour was too good for the oil.

There also aren't that many reports on the 4b11T motor in the UOA section.

I just checked the oil on the dip stick and a) not a single drop burned and b) still clear, just slightly brown (not black). Maybe i'm being paranoid...

 

[donnyj08]

I believe that motor is based off of the 4G63T, which was a stout little mill as long as one could keep a timing belt on it. I had one of those years ago. I ran M1 10w30 at 5K OCI's and i raced/ran that thing hard all the time with a Evo3 16G turbo @ 18psi and other mods. I never had an issue with it.

As long as you let it idle a min or two after a long run to cool the turbo it should be fine.

I once drove from Evansville, IN back home to Madison, IN doing 100mph+ Rpm on I-64 as a teenager in my 1998 GST. The RPM's were over 5k for over and hour straight, rolling into full boost going up every long hill. I remember stopping to pee and i pooped my hood while i was letting it idle to cool and the turbo manifold was glowing bright orange. I left it running, came back out and cruised on home. That engine was so spotless when looking through the fill hole.

I'm glad i no longer drive like that, It was fun tho! me and my sister made that 3 hour trip in 2 hours and 5 mins with a pee break.

 

[CT8]

Syn thet ic oil.

 

[SilverSnake]

I would change the oil. Very cheap insurance.

 

[Clevy]

Originally Posted By: SilverSnake
I would change the oil. Very cheap insurance.



How is it cheap insurance? If anything he cooked out any fuel dillution and moisture which is good.


That cheap insurance comment always brings me a chuckle.

 

[barkingspider]

change the oil at your normal interval

 

[Johnny2Bad]

Do you have a vacuum/boost gauge in the vehicle? (If not, install one). If you were only running moderate boost everything should be fine. But if the turbo was working hard, check the oil, give it a smell. If it looks OK carry on, if any issue at all change it.

 

[sicko]

QSUD still has plenty of life left in it after 4500-5000 miles, so even if that stint on the highway reduced the life expectancy of the oil/additives, it should still be fine by the time you're changing it out at around 4500-5000 miles.

 

[Merkava_4]

Originally Posted By: xil
The motor was at 4500-5000 rpm for over an hour straight on the interstate, I'm sure the turbo was glowing red hot the whole time.


How'd you manage to do that? Did you lose one of the speeds out of your transmission? My car turns less than 2000 rpm at 70 mph and I thought most other cars did as well.

 

[Olas]

Originally Posted By: Merkava_4
Originally Posted By: xil
The motor was at 4500-5000 rpm for over an hour straight on the interstate, I'm sure the turbo was glowing red hot the whole time.


How'd you manage to do that? Did you lose one of the speeds out of your transmission? My car turns less than 2000 rpm at 70 mph and I thought most other cars did as well.

It's entirely dependant on tyre size and gear ratio.

I can wind second right up to 7200 rpm for an indicated 70, or I can let 5th sit at 2200. Plus he says nothing of how fast he was going keeping it spinning at 5k.. Not hard to believe at all IMO.

 

[hpb]

It'll be fine, leave the oil for its usual interval. Cruising at constant high revs, but low load, doesn't work a turbo very hard. A track day, or a hard run up your favorite mountain road, where you're running it to the redline, backing off, and doing it all over again, puts far more stress on them. Plus, this engine revs out to what, 7 or 8,000rpm? 5 grand only represents two thirds of its operating range, so plenty left in reserve.

Merk - I'm guessing you haven't driven anything with a small capacity engine in the last 30 years or so...

 

[xil]

Don't have a boost gage but I'd wager I wasn't at very high load. I took a whiff of the oil yesterday and nothing unusual.

The car in 6th gear turns at 3k. I believe it rev's out at 7k? I usually upshift below 5 and only hit redline maybe 2-3 times a week. Its not a new car, most cars now have 7 to 8 speeds and in top gear probably do low 2k's at highway cruising speeds.

It doesn't help that I picked up a jug of Pennzoil platinum that morning. Idle hands...