Oil switch for GM 3.4L and 3.5L

[Hardware_Monk]

I acquired 2 high mile vehicles, a Venture 3.4 with 175k, and a Malibu Maxx 3.5 with 115k. Both engines were mechanically quiet when purchased directly from a company fleet.

I have tried to switch them to better oils, including commercial oil, and/or synthetics.

Since then, both have rapidly deteriorated: cold-start noise, hot idle noise, and some noise under accelearation - none of which were present upon initial purchase. It is very disheartening, and portentially expensive.

The deterioration seems to stem from changing the weight/grade/type of oil in an apparently doomed effort to help preserve these motors. Now, nothing I do seems to stop the downhill slide.

Rotella 15w40 was plainly too thick for the 3.4, even at 175k. A decent 10w-40 conventional was OK during a trip south, but broke down very quickly. A change to 10w30 for the last of the cold weather gave me more noise. When the weather warmed, I used Valvoline's synthetic blend in 10w-40, which used to be very good, but now broke down very fast. Rotella 5w-40 held up well, as always, but did not stop the audible increase in wear until far too late.

The 3.5l didn't do well on a 10w30 conventional oil, but rejected the Rotella 5w-40 immediately. Lucas 10w30 synthetic is doing nothing to stop the increase in noise. Draining a quart to add their oil stablizer helped for the first part of a long weekend trip, but by the time we got back, each cold start seems to be noisier (just now read the recent post where opinions were thumbs down on Lucas).

Is it simply a case of "don't change to synthetic after 100k" (which never bothered my 4.3L engines) or do these motors have unique demands? I have never, ever, seen this kind of rapid increase in mechanical noise, including the earlier 3.1L and 2.8L predecessors.

Should I give up and switch back to 5w30 dino, or is it too late, and I should put in the PP 10w30 I have behind the seat?

 

[daves87rs]

What about Maxlife?

 

[SLCraig]

I'd have no problem just saying switch back to what the vehicles were on before you acquired them. See how that goes...

 

[postjeeprcr]

Originally Posted By: SLCraig
I'd have no problem just saying switch back to what the vehicles were on before you acquired them. See how that goes...


I agree. what made you switch weights of oil when you said everything sounded fine?

 

[Herz]

Use what the cars were using. especially since it worked.

No fancy oil will save a engine that is doomed to death anyways.

Good luck hope the problem goes away

 

[Neil_A]

Both those motors should be spec'd for 5w30 why go higher?

 

[addyguy]

Has the intake manifold gasket been done on the 3.4? If not, you might have a coolant leak, oil sludge, and potential engine failure.

These engines do get noisy as they age. It's nothing really to worry about, they are just noisy engines. Don't stress yourself out about it too much......

 

[Kruse]

Originally Posted By: Hardware_Monk
I acquired 2 high mile vehicles, a Venture 3.4 with 175k, and a Malibu Maxx 3.5 with 115k. Both engines were mechanically quiet when purchased directly from a company fleet.



I was recently given a '98 3.1 Monte Carlo. It was given to me because the previous owner had new lower intake manifold gaskets installed by the dealer and they had again failed. He was tired of the repair costs. I drove the car home from where he had it (~25 miles), replaced the intake gaskets with Fel-Pros and by the time all the oil had dropped, I got out about 7-8 quarts of a tan colored froth, with the consistency of a whipped up milk shake.
I put in 5W-20 for 500 miles and will probably drop the oil again tonight to get the rest of the contaminants out of it and replace it with 5W30. Oil looks good and the car runs good. Car currently had G-05 coolant installed.
I would put in what the manufacturer recommends instead of the thicker oil, use a good filter and see if you get better results.

 

[Zaedock]

Originally Posted By: Hardware_Monk
I acquired 2 high mile vehicles, a Venture 3.4 with 175k, and a Malibu Maxx 3.5 with 115k. Both engines were mechanically quiet when purchased directly from a company fleet.

I have tried to switch them to better oils, including commercial oil, and/or synthetics.

Since then, both have rapidly deteriorated: cold-start noise, hot idle noise, and some noise under accelearation - none of which were present upon initial purchase. It is very disheartening, and portentially expensive.

The deterioration seems to stem from changing the weight/grade/type of oil in an apparently doomed effort to help preserve these motors. Now, nothing I do seems to stop the downhill slide.

Rotella 15w40 was plainly too thick for the 3.4, even at 175k. A decent 10w-40 conventional was OK during a trip south, but broke down very quickly. A change to 10w30 for the last of the cold weather gave me more noise. When the weather warmed, I used Valvoline's synthetic blend in 10w-40, which used to be very good, but now broke down very fast. Rotella 5w-40 held up well, as always, but did not stop the audible increase in wear until far too late.

The 3.5l didn't do well on a 10w30 conventional oil, but rejected the Rotella 5w-40 immediately. Lucas 10w30 synthetic is doing nothing to stop the increase in noise. Draining a quart to add their oil stablizer helped for the first part of a long weekend trip, but by the time we got back, each cold start seems to be noisier (just now read the recent post where opinions were thumbs down on Lucas).

Is it simply a case of "don't change to synthetic after 100k" (which never bothered my 4.3L engines) or do these motors have unique demands? I have never, ever, seen this kind of rapid increase in mechanical noise, including the earlier 3.1L and 2.8L predecessors.

Should I give up and switch back to 5w30 dino, or is it too late, and I should put in the PP 10w30 I have behind the seat?



My wife's '04 Maxx runs fine on 10W30 and I am about to return to 5W30 QS green bottle for winter. I recommend returning to what the fleet used. FWIW, what brand gas do you use? My wife's Maxx has a hint of piston slap when cold and typical GM engine noise.

Also, you stated that the Valvoline syn blend "broke down". Did you do a UOA to determine this? Also, an audible increase in sound does not necessarily mean an increase in wear.

 

[gizzsdad]

I can't help but wonder if an additive was added before you bought them in order to quiet them down??

 

[Hardware_Monk]

Thanks very much for all the input!
The Valvoline I tried was the Maxlife. I tried this and other heavier weights, as the miles were high on them, and assumed they were a bit looser.
I was my understanding, talking to dealer mechanics in the past, that the 5w30 oil spec was exclusively for EPA mileage rating tests, and the engines had tolerances no different than were traditional. I have always run 10w-40 for 3 seasons, and 10w30 for winter.

Rotella 15w40 has done wonders in the past in other older engines, with no weight-related issues. It may be that the engines are now truly different internally.

Yes, it had actually occurred to me that a judicious application of some "Motor Honey" may have been done when put up for internal bidding...

I had looked the 3.4 over for gasket issues, and found no signs of it, or of prior repairs. Got a good one, it seems.

I experimented with gasolines, and found that a private station locally that gets (I'm told) Canadian gas, always ran best in all vehicles. The 3.4 and 3.5 show a preference for the 89 instead of their 87.5, even after using carbon-cleaning additives initially.

Returning them to 5 or 10w30 is my approach, I think, but should it be dino, as they had used, or continue the synthetic route, now that I've started using it?

An oil change place locally said (after it I'd already done it) not to switch to synthetic, but whatever I do, don't switch back, once I did go synthetic...

 

[il_signore97]

Originally Posted By: Hardware_Monk

Returning them to 5 or 10w30 is my approach, I think, but should it be dino, as they had used, or continue the synthetic route, now that I've started using it?

An oil change place locally said (after it I'd already done it) not to switch to synthetic, but whatever I do, don't switch back, once I did go synthetic...





You can feel free to use whatever type of oil you like, either synthetic or dino. I personally have a preference for a good synthetic, but it's not without downfalls on high mileage vehicles. For one, you don't know the oil change history of these vehicles. They may be in good condition, but could have some build-up within them from extended OCI's on dino oil. The syn oil may begin to dislodge some of the build-up causing noise, plugged filters, etc. All this means is that you may have to change your oil frequently, either with dino or syn. The cars could also have bad seals, being held together by the build-up of crud from extended OCI's on dino. The syn will eventually clean this up and expose a leak if there is one. If not, then you're good to go, but you won't know for sure...

Also, both of these engines run best and stay quiet with the thinnest oil possible at cold start-up. This means that if you use a syn, you should try to grab some 0W30, or 5W30 at the most. Mobil 1 0W40 is an excellent choice for these motors if you want to up the hot running viscosity a bit.

I have a Venture 3.4L V6 with 170,000 miles on it. It's been on dino for the first 50,000 miles, with 5000 mile intervals, and then on Amsoil 0W30 syn ever since. It does all city driving in terrible conditions, and it's never been quieter than with the 0W30. There will always be some piston slap on a cold start, but it goes away very quickly with the 0W30.

Maybe some Auto-RX or Amsoil Engine flush might be in order, and a few shortened oil changes would be beneficial.

 

[Hardware_Monk]

Thanks, its very helpful to have some insight from another owner of these motors.

I definitely noticed their preference for thinner oil during startup, but I do think they need a hot oil spec that's not too thin. Some oils failed to easily for my comfort level.

I had previously mentioned noticing oil breakdown, but hadn't explained. I've never done a a formal UOA, but for years I've done what I eventually called the "slip test".

When I have reason to question the life remaining in the engine's oil, I'll swipe the oil off the end of the dipstick, and rub it evenly between the tips of my thumb and forefinger.

At this point I pause, squeeze thumb to fingertip, and try to slide them across one another. It doesn't sound scientific, but it has been a very valuable as a "go, no-go" gauge.

Basically, failed oil will allow your fingerprints to catch, and prevent your thumb and fingertip from sliding under pressure. Acceptable oil will have a base lubricity you cannot squeeze out from between the thumb and finger surfaces.

It may seem all the same on the first few tries, but when you hit your first good case of failed oil, it will be a "cringe-worthy" moment you won't forget, imagining what must be happening with it under true bearing loads in a running engine...

I will have to check the shelves again in my area, and see what I can find that has a lighter startup weight. Experimenting with the synthetics at this point will give me some short changes, and should help the clean-out process, if there are deposits to remove.

My impression is that these motors didn't lack for oil changes, but had just run average factory spec oils. Now that I disturbed the groove they were in, I hope to get my choice of new oil corrected quickly.

I do hope to hear these motors quiet down again...

 

[wgtoys]

"I had looked the 3.4 over for gasket issues, and found no signs of it, or of prior repairs. Got a good one, it seems."

What model year? It is hard to imagine a GM 3.4l with 170k miles which never needed the intake manifold gaskets replaced and which isn't leaking.

 

[Kruse]

Originally Posted By: wgtoys
What model year? It is hard to imagine a GM 3.4l with 170k miles which never needed the intake manifold gaskets replaced and which isn't leaking.


I suppose there are a bunch of high mileage engines out there with no problems, but if I had a 3.1/3.4 with that many miles on the original intake manifold, I think I'd put new ones in just for the peace of mind. Except for the visible RTV bead between the intake manifold and the block, it's hard to tell that the engine in my car has ever been touched.

 

[addyguy]

Failure rate of 3.4 IM gaskets is approaching 100%. If it hasn't gone, it will go. If it doesn't fail catastrophically, it may leak slowly for years, and slowly wreck the engine.

 

[Hardware_Monk]

The Venture 3.4 is a 2003. A friend of mine who does dealer work looked at it, and said it didn't look like replacement gaskets to him. In addition to visual clues, the company service record that came with it makes no mention of any such work being done.

When I was looking at Impala's and Malibu's, a helpful used car guy mentioned the 3.4 intake gasket issue, but said that he'd also seen some that simply didn't develop the problem. He was basing that on long-time repeat customer history(s).

I'll keep the warning(s) in mind, and if the oil problem gets settled OK, it may be worth putting in the shop to get the gaskets done for prevention.

A formal oil analysis might also give an early warning, I suppose...

 

[saberz]

Well it could be due to poor OCI maintenance on the fleet's part. You changing the oil out and swapping in newer oil, different weight etc could be dislodging any buildup in the engine? Just a thought? I mean look at the Saturn Vue fleet vehicles from Enterprise, they were sludged due to poor maintenance.

 

[wolfc70]

The 3.4 gaskets were most likely replaced under warranty, as the 2002-2004 years seem to fail before 36k miles. The "new" gaskets have torque stops to help prevent gasket tearing from the rate different metals expand at. My family has many of the 3.4l v6, form Grand Am's to Rendezvous. All had the gaskets fail.

The 3.4l engines like thin oil, and for some reason, lifter noise and piston slap when cold is quite common, I have never heard one of these engines start cold and not make horrible noises, but they do seem to last if cared for though. Some seem to burn oil, and some do not. My sisters 2003 Grand Am burned a quart every 1500 miles since it was new. My uncles 2003 Rendezvous does not, so it all depends.

 

[il_signore97]

Originally Posted By: Hardware_Monk
Thanks, its very helpful to have some insight from another owner of these motors.

I definitely noticed their preference for thinner oil during startup, but I do think they need a hot oil spec that's not too thin. Some oils failed to easily for my comfort level.





If you're concerned with the longevity of factory-spec oils in these vehicles, I can assure you that any synthetic 0W30 will exceed your requirements. I have never been dissatisfied with the results (based on both UOA and subjective items -- look and feel, engine sound, etc) of any 0W-xx synthetic oil.

Having said that, if you want to run a thicker oil for peace of mind, Mobil 1 0W40 is the way to go (or a similar spec oil from Redline, Amsoil, etc, etc). It is very thin upon start-up, but will keep a 40 weight viscosity at operating temperature, just a tad thicker than your typical 30 weight.

I run 0W40 in my 3.4L (actually its in there right now) during towing season, sometimes switching back to 0W30 or even 0W20 in the winter due to no towing, all very short trips, and very cold weather. And I wouldn't worry about a 0W40 shearing in this engine - it's very easy on oil in that regard.