Full Synthetic 15W-40 Diesel Oil okay in 2004 Vortec 4200 VVT Gas Engine for Cleaning?

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I am a Newbie here and This is my second time posting on here with a question. I have just bought a 2004 Chevy Trailblazer with the Vortec 4200 VVT I6 Engine with 153,000 miles on it. I did not get any service records with the vehicle when I bought it so I don't know engine oil change history, I.E. What type of oil used. change Intervals. etc. Even though it does not seem to use any oil I don't know how dirty the inside my engine is, I would like to clean it up just for added insurance. My question is: '
1. I was told even though it is a gasoline engine that running a good quality 15W-40 weight "Full Synthetic Diesel Oil" a couple of times through it would clean my motor up very well just in case it is dirty inside. Yay or Nah? Safe or Not? Thanks for any and all help!
 
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I am a Newbie here and This is my second time posting on here with a question. I have just bought a 2004 Chevy Trailblazer with the Vortec 4200 VVT I6 Engine with 153,000 miles on it. I did not get any service records with the vehicle when I bought it so I don't know engine oil change history, I.E. What type of oil used. change Intervals. etc. Even though it does not seem to use any oil I don't know how dirty the inside my engine is, I would like to clean it up just for added insurance. My question is: '
1. I was told even though it is a gasoline engine that running a good quality 15W-40 weight "Full Synthetic Diesel Oil" a couple of times through it would clean my motor up very well just in case it is dirty inside. Yay or Nah? Safe or Not? Thanks for any and all help!

Before deciding on a course of action pull the oil fill cap and the pcv hose off. Take a look, maybe it’s not that bad.

my personal choice would be a pcmo and shorter interval on the oil change. Try super tech and go 2,000 miles and see what it looks like.

Just my $0.02
 
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Before deciding on a course of action pull the oil fill cap and the pcv hose off. Take a look, maybe it’s not that bad.

my personal choice would be a pcmo and shorter interval on the oil change. Try super tech and go 2,000 miles and see what it looks like.

Just my $0.02
Yep, just like nearly every “I want to clean the engine” post there’s no indication it needs cleaning.
 
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To answer your question without criticism, using a 15w-40 won't do any harm and should be perfectly safe to use in summer.

As to cleaning, perhaps whoever suggested that was thinking about Valvoline's Premium Blue Restore, which would do a hella good job cleaning.

Agree with taking a look inside the oil fill and pcv to see what it looks like.
 
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Just my personal opinion here. I will occasionally use a HDEO 15w40 with 20-25% MMO at 3k or so for a good cleaning. Getting ready to do an annual run of this mix in my 2008 Corolla.
 

Nitro1320

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To answer your question without criticism, using a 15w-40 won't do any harm and should be perfectly safe to use in summer.

As to cleaning, perhaps whoever suggested that was thinking about Valvoline's Premium Blue Restore, which would do a hella good job cleaning.

Agree with taking a look inside the oil fill and pcv to see what it looks like.
Thanks...:)
Yep, just like nearly every “I want to clean the engine” post there’s no indication it needs cleaning.
Yep, just like nearly every “I want to clean the engine” post there’s no indication it needs cle

Just my personal opinion here. I will occasionally use a HDEO 15w40 with 20-25% MMO at 3k or so for a good cleaning. Getting ready to do an annual run of this mix in my 2008 Corolla.
Any Particular Brand of HD 15w-40 you like? That is Conventional oil you run? No full or Syn blend?
 
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Thanks...:)



Any Particular Brand of HD 15w-40 you like? That is Conventional oil you run? No full or Syn blend?

most of the HDEO are at least semi synthetic now. Every reputable manufacturer makes HDEO in one flavor or another. Pick your favorite brand and go. I use Mobil Delvac 1300 in my Cummins with good results but I’ve been eyeing Mystik JT8 recently due to cost. In my truck forum most guys seem to use Rotella, Valvoline, Delo and Delvac. There’s a few boutique oil guys as well.

just my $0.02
 
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I'm gonna say full capacity (7qts?) of Mobil 1 0W-40.
Feel free to Substitute 1qt of oil for 1qt of Marvel Mystery Oil. Or 1qt of Rislone 100QR Engine Treatment Conditioner and Cleaner.


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The 4.2 is not known to sludge but a good place to look for any is on the VVT oil control solenoid. You have to move the power steering pump somewhat but on bolt and it will slide out. It has a very fine screen and will show you sludge or varnish if your motor is gunned up.

Personally I would just run a shorter change index with some cheapo 5w30 conventional with a decent filter and call it a day.
 
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These engines all get super varnished on the inside due to the design of the crankcase vent system expect under the timing cover and under the valve cover to be very varnished, while it's not aesthetically pleasing, pretty much every single Vortec 4200 has this heavy varnish when you open it up, don't worry about it.
 
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Not sure where you are located, but if you live in a warm climate, you could use 15W-40 year round with no issues.

If you are worried, pick up a decent oil (if you want HDEO, go with something like Delo 400 XLE 15W-40) with a decent filter, like a Fram Ultra XG9837, and reset the oil life monitor. Check the condition of the oil, and oil level regularly until your oil life drops to 80% (for me this is about 1,900 miles) and add two cans of Liqui-Moly Oil Sludge Remover. Drive the vehicle an additional 250 miles while keeping an eye on both level and condition and change it all out.

Reset the oil life monitor again, and keep an eye on the oil until oil life drops down to 80% and add two cans of Liqui-Moly Pro-Line Engine Flush to the oil at operating temperature and allow to idle for 30 minutes straight. Drain the oil, replace the filter and you should be set.

As previously mentioned, varnish can be a bit of an issue with these engines, and what I described above has helped me tackle oil consumption issues with quite a few LL8 engines. The PCV system on this application, IMHO, is not exactly the best design out there and you might want to consider installing an oil catch can. Doesn't have to be anything fancy, just something that'll do the job efficiently. Just pull the hose off on the center of the intake manifold and connect your catch can there. You'll notice less oil build up in the resonator, throttle body and the vent hose on top of the valve cover as well.
 

Nitro1320

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Before deciding on a course of action pull the oil fill cap and the pcv hose off. Take a look, maybe it’s not that bad.

my personal choice would be a pcmo and shorter interval on the oil change. Try super tech and go 2,000 miles and see what it looks like.

Just my $0.02
Thanks.... :)
 
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