1997 Monte Carlo w/GM 3.1L + 126K miles; which oil?

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May 27, 2003
Elkridge, MD
Hello all, I followed a link from mymonte.com, which is a board I freqently browse and post at to this site. I've been driving my car for the past 13K miles and I've been using Castrol GTX 5W-30 and Purolator Premium Plus and more recently PureONE oil filters. I have not had a problem with this combination, my engine burns remarkably little oil for its age (usually 1/2 quart every 3,000 miles) and is still very strong for what it is. The car had been taken care of its entire life and 5W-30 has been used in it and changed every 3,000 miles or less religiously. Until I started driving and maintaining it, it was subject to almost entirely highway miles and light driving conditions. With the breif history stated, let me tell you a little about my current driving habits. I drive around 35-40 miles per day, but it is not uncommon for me to drive farther...I drive around 300 miles in the average week. I go through about 6 or 7 start/stop cycles per day. I live in a hilly, but not particularly mountainous area, so the car does its fair share of hill climbing, and occasional very sharply inclined roads. I also will confess that I have a heavy foot. My starts are not full throttle launches, but moderate starts usually bringing the motor to 3-3.5K. This is mostly due to the fact that the little 160hp 3.1L is hauling the relatively heavy Monte Carlo and usually a few passengers and a trunkload of stuff. I keep the car out of its 'preformance enhancement' (which engages at more than 70% throttle) mode under normal circumstances. I think I treat the car pretty well. I run regular gas most of the time, but will occasionally treat it to premium. I continue to change my oil every 3,000. My car is quipped with one of those "Change Oil Soon" sensors, but I don't trust it and always change at 3,000 at the latest. Now that you know a little more about me and my car, I think you can better understand my oil situation. As I have said, my car seems to operate well with 5W-30 year round as well as a Purolator PureONE oil filter. I have been told that I should switch to 10W-30 for added protection during the summer months. What are your opinions on this? I am very happy with the PureONE oil filter, but I am running the stock recommened length. The filter my car calls for is the PL10111. There is however, a PL24011 filter which is an extended length which I know to fit my motor. I have been told to use the extended length filter along with a full 5 quarts of oil (I reguarly use 4.5 quarts) for better filtering preformance under higher pressures. What are your opinions on this? I don't really see how I can harm anything in doing so. I don't see myself changing to a synthetic for a motor which has already endured 126k miles with petroleum oils. So to summarize: What weight oil should I be using? 5W-30, 10W-30, or something else? (I'd prefer to use either the 5W-, or 10W-30 because they are recommened by the owner's manual, but I'm open to other opinions.) Also, what do you think about my choice of filter (PureONE) and would it be beneficial in changing to the extended length? (I would still be changing my oil every 3,000 or less). Thank you in advance for your insight.
Welcome to the board I have owned a couple of the 3.1's . I think that Castrol is a fine choice. I would lean to the 10W-30 for summer. The oil will stay in grade better-but with 3K oil changes it really doesn't matter. I would definitely go with the longer filter if there are no interferences with the frame. Remember the engine will rock in its mounts so make sure it is well awar from a frame menber. BTW have you hade to replace the Intake Manifold gasket yet?? That engine would be an excellent candate for 7K oil changes with Mobil 1 10W-30. [Welcome!] [ May 28, 2003, 07:22 PM: Message edited by: Al ]
Hi, thanks for the welcome. I suppose I will try the 10W-30 then. I had been told by a few people that 5W-30 doesn't coat or protect worth anything, and that 10W-30 is a big improvement. From your reply I am gathering that over time 5W-30 is more prone to degrading, where as 10W-30 won't, but they are equal in their ability to coat and protect. I guess in my case it doesn't really matter if I use the 5W- or the 10W-30 since I change every 3,000 miles. The longer filter fits fine on my 3100 in the Monte. It is a transverse mounted FWD car, and the filter location is facing the front of the car, so when the motor swings back from torque it rocks away from obstructions (at least in the case of the oil filter). Yes, I did have to have my Intake gaskets replaced at 120K miles. They were damaged and leaking when I acquired the car, but the coolant was leaking out of the motor and burning up on the transmission casing and rear exhaust manifold. I just kept adding coolant to keep it filled. At an oil change I noticed that there was some coolant mixing with the oil and it was at that point I had them replaced to the tune of $600. Poor gasket material on this motor. GM finally released a revised design after who knows how many years, but it was after I had my gaskets replaced. (They were replaced in January) I guess next time around I will get the revised design. As far as the synthetic is concerned, if for some crazy reason I do decide to switch, can I just change right over, or are there other steps to take? I have heard stories of synthetics causing older motors to burn more oil and develop leaks. While, I'm pretty sure this is a myth, it is not something I can risk financially right now. Should I use 10W-30 year round, or should I use synthetic 5W in the winter? Thanks for all your help.
Probably in N.Y you should go with the 5W in winter. Just to be safe. Even though I am a big synthetic oil person, I can't really blame you for sticking with what works. If you decide to switch at some point-some would recomend a product called AutoRx as a clean-up before using synthetic. I'd probably just switch and change at normal intervals for a couple of times. But hey-you are doing O.K. with the Castrol. BTW how many altinators have you used yet [LOL!] Sorry I couldn't resist it. [Smile] (another 3.1 weak link)
If you keep changing your oil at 3K miles, then don't alter your current routine. Both 5w- and 10w-30 are just that--30 weight oils when warmed up. It is often the case that 5w oils thin out more quickly than 10w oils, but that is typically under conditions of abuse or long intervals. If you stick to your current intervals, that won't likely happen, and you'll get a little better lubrication at startup with a 5w oil, particularly during winter. As the engine ages, though, you might graduate to a thicker oil, like a 40 weight, to slow any consumption problems that might arise.
mstrjon32, I have an identical car. I have used pure ones and Trop-artic since new and with 3k interval changes have no noticeable consumption at 72k miles. I recently changed to Wix with the longer filter after reading posts on this forum. The longer filter is easier to reach as an added bonus. One time, I let the filter wrench hit the starter and it spot welded a pin hole in the filter! Luckily I saw the mess on my garage floor before I drove away. I am considering trying Mobil 1 5-30 just to see if it will help with the slight piston slap upon cold start up. My main concern of switching to 10-30 is not enough lubrication on cold starts, even summer cold starts. I had the intake gaskets replaced also. Keep me posted with any new happenings with your car.
Totally agree with the consensus. I've been religously using Purolator filters, both short and long and love them. Easily accessible. I'd stick with the 10W-30. My 3.3 GM V6 has 171K on it and went from the recommended 5W-30 to the 10W-30 with somewhat noticable results. Been using Pennzoil, but I may, after reading UOA on it, may make the jump to Pennz. high mileage.
Thanks for all your replies. I will change over to the longer style oil filter and just put in a full 5 quarts on my next oil change. I will also give the Castrol GTX 10W-30 a try for the summer months. It seems as if it holds its grade better during the course of an oil change interval. I guess it can't hurt as it is supported by the manufacturer. Also, the alternator has never been replaced on my car. (Knock on wood) It is a Delphi Automotive alternator however, not the supposedly more troublesome Delco Remy alternators found on earlier 3100's and 3.1's.
re: "I will change over to the longer style oil filter and just put in a full 5 quarts on my next oil change." On my 1997 Lumina, if I put in 4.5 quarts, the oil is above the FULL mark on the stick, even with the larger filter. I don't think another 0.5 quart will hurt anything, but I have to wonder if the benefit is significant. By the way, I am using Rotela T 5W40 (available at Wal*Mart(, which seems to be very well suited to the 3.1.
My car calls for 4.5 quarts. When I fill the oil filter and put the remaining directly into the motor, before I start it the first time is is about 1/16 inch below the full mark on a perfectly level surface (my garage) with cold oil. So that seems about right. If I fill it up with the longer filter which will probably hold a little under 3/4 a quart (I'm guessing, I'm not sure how long it is exactly yet) I will be 1/4 quart over, which will probably put me at the full mark before that first start. I want to stick with a Xw-30 oil because its in the owner's manual. I'm a firm believer in that the people who made the car know what is best for it. I would consider a heavier weight oil if it was an severe oil burner, but it's burning about 1/2 a quart every 3,000 so I'm not too worried about it. That said I'm going to try the 10w-30 during the summer as it will supposedly hold its grade better and protect for the life of the motor, but hey whatever works for your car.
I was doing doing some searching and it turns out the AC Delco Ultraguard Gold (UPF-52) is still made! This is the equivalent extended-length filter for my car, part number 25322836 and you can get it from GMpartsdirect.com. I will order this and give it a try for my next oil change over the PureONE. Supposedly these are some of the best filters out there. I didn't realize that these were still available for my car...I thought they had been tottally discontinued. Turns out they still make the UPF-52 as well as the 44 (not sure what that one fits).
Originally posted by mstrjon32: My car calls for 4.5 quarts. When I fill the oil filter and put the remaining directly into the motor, before I start it the first time is is about 1/16 inch below the full mark on a perfectly level surface (my garage) with cold oil. So that seems about right... I want to stick with a Xw-30 oil because its in the owner's manual. I'm a firm believer in that the people who made the car know what is best for it.
Interesting that my car seems overfilled when I fill it to "capacity" while yours is slightly underfilled. I wonder why? I would do the same thing as you on the oil grade. Mine is consuming oil and this 5W40 is helping a lot. However, if you do some reading on here, you will see that a lot of people feel the "people who made the car" are more interested in the car getting 0.2 mpg more than they are with how long the engine lasts. Higher CAFE numbers mean they can sell more profitable vehicles. Thanks for the tip on GM parts direct and those good oil filters. Prices are really good there but the shipping seems outragous (to me). There are a couple neat items you might consider from GM Parts Direct (or your favorite GM dealer)... An engine compartment decal that says to fill with Mobil 1 that is used on certain Camaros and Corvettes GM # 10236268 and a oil filler cap for certain Camaros and Corvettes (fits other GM cars) that says Mobil 1 on it GM # 12555685. [ June 03, 2003, 10:13 PM: Message edited by: CJH ]
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