The acdelco pf47 and pf52 are the same filter. The pf52 is just longer.

Good suggestion on the longer filters Mike, here is a pic I saved of longer filters that fit the 3800 II.

The argument goes on and on and on..... and in the process, the real issue slides right on by. It has been proven time and time again, the Mobil 1 synthetic oil(along with other industry leaders brands) viscosity does not fall below required certification standards when pushed to 10K or even 15K with the new Mobil 1 Extended Performance. It'* truly a moot issue but hard for many to let go. HOWEVER, in the process of worrying about the oil, the main problem with extended oil change schedules is sliding right under everyone'* radar.

The oil filter becomes the issue when we extend the oil changes to 10K or even further. You run the entry level Fram PH3980 by chance? If so, you should NEVER extend your oil changes if you even put one of these pieces of garbage on your engine. How about a Motorcraft? Same story. Most regular filters have extremely poor bypass valve designs which can actually allow dirty oil and even solid particles suspended in that oil to totally bypass the filter internally. Quit worrying about viscosity and focus on the filth building up in the oil and you will be enlightened and find great peace and harmony with your engine and your oil!!

Research the filters and find out which ones actually are designed internally to continuously filter the oil, never allow oil to just wash over the filter element and let large particles reenter your oil system and what the element is actually made of. I came to the conclusion that it takes a little of both philosophies to give yourself the best chance to maximize your lubrication system AND get the most your oil has to offer. Run the oil to the specs from the vehicle manufacturers extended schedule BUT continue to change your "quality" oil filter at regular old school intervals such as 3K to 5K with a touch of top off to maintain the proper oil level.

Trust the engineers and scientists - the synthetic oils can make the mileage they guarantee but it MUST be coupled with a QUALITY filter. I'm totally happy with Mobil 1 Extended Performance claims and quality BUT I feel more comfortable changing the filter at 5K intervals and then a new filter AND new oil at 10K/15K, whichever they specify on the oil. I have 159K on my GP GT and my oil pressure doesn't drop between changes, the inside of it sparkles and my oil analysis test at 150K looked like a practically new engine. Sometimes we can't see the forest for the trees......

I have to completely agree here. Every engine is different, so what is good for one engine may destroy the next one. The only safe way to stretch oil change intervals is with regular oil analysis. That will tell you what your limits are and point to upcoming issues very quickly.

But who can afford or has the time to wait for analysis to come back? Some kits are around $25 and to spend another $25-$50 for the test itself. Is it really worth it? IMO, the oil pressure gauge is an excellent tool that if used in conjunction with other variables can tell you if your oil is on its way out.

What some scientists says in a lab, can stay in a lab for all I care.

Agreed, I have a oil analysis kit that I got for free like 2 years ago, never got around to having the money to pay for the analysis, they wanted around 25.00 to return the results.
I just ran a rare earth magnet through the oil to see if it picked up any metal shavings or bits, and looked at the color or it, that told me enough to realize I just needed to change the oil.
Granted you get much more detailed info from the analysis, I just don't see that as a necessity unless you mod/race your car.

I do agree with the comments on the oil filters, but I don't understand why one would put the oil back in at 5k, no matter if you change the filter or not I still think putting the old oil back in is not the best thing to do, even if the manufacture claims it can go 10-15k.
If you care enough about the motor to get an oil analysis done, then why wouldn't you spend a little more money when changing your filter, and put some fresh Mobil 1 Synthetic Oil in there?
After all I spend around 38.00 to get the 5 quart thing of oil, not a lot more than the price of an analysis.
Now I am not saying an analysis is not useful if you want to keep using your old oil just for the sake of only changing it at the manufactures recommended intervals, I just don't understand why anybody would put old oil back in there, whether or not it still has a little life left on it.

I like the analysis for one reason and that'* as backup information on certain metals that tell a lot about the bearings and other parts. I suppose I cheat since I still have connections at the base and get a sample shot for free here and there. At the current cost of high end oils, changing the filter between extended oil changes is much more economical than throwing out 5 quarts of gold long before it'* life expectancy is reached. It takes me about 10 minutes to slide under the car, change the filter, add a half quart back in to top off the level and press on. I don't remove the oil and reinstall it if I read the comment correctly. As for the color of oil, this is an exert from Mobil discussing dark colored oil: We would never use color alone as an indication to gauge whether or not you should change your motor oil. Without oil analysis you can reach the wrong conclusion about oil quality and in many cases darker engine oil is not a sign of any issue or problem. Some additives used in modern oils can produce a dark color over time and this is normal. It is best to change your oil based on time in months or miles. Of course, the number of miles and months depends on many things like service, climate, engine condition, etc.

I trust the oil to last as they guarantee but why not help keep the extra unwelcome particles out. Remember, I live in the dusty azz desert and that darn dust gets into everything. I have to clean my K&N filter out here a lot sooner than I did back home. Same goes for my cabin air filter. If I was rich, I'd think nothing of changing out $35 - $40 worth of oil at much shorter intervals but it'* just not necessary. I've always run the longer truck filters but oil filter technology has not kept up with oil technology so a new larger filter at earlier intervals is inexpensive insurance.

We all have our ways we feel comfortable with and I respect each and everyone'* opinion. I spent a career working on high performance jet engines, smaller gas turbine engines in ground equipment and everything from lawn mower engines to large prototype diesels. The study of oils, their formulation and properties are engrained in my brain and I try and keep up with technology updates as much now as before. I think it'* hard with some issues to place our trust in certain things because there are incidents that make us doubt. Parts fail, things wear out and engines go pop. A lot of times it'* simply because of bad decisions, improper repairs or poor maintenance and people don't always tell us all the facts leading up to those failures. Oil is one of the players that more times than not gets a bad wrap and all the blame.

Wasn't sure exactly where to post this but this turns oil technology on it'* head! They've been working on this technology since the gas shortages of the 70'* and it'* finally come to fruition. We should invent a new perfect oil filter for this stuff and get fat rich!!! Synthetic Motor Oil from Natural Gas | Pennzoil PurePlus

How many different metals are the internals made up of?
The only ones I can think of are aluminum, and iron, and if you get traces of either you still have to play the guessing game as to just what it came from, unless the analysis can better pinpoint the problem than I am imagining.
I'm not saying having one done is a bad thing, just that money is limited for myself also, and I find it cheaper to go ahead and change out the oil every 5k, or after a certain length of time, rather than to pay 25.00 for an analysis , then find out the viscosity has broken down to the point that it needs to be replaced, so it is not as much about comfort, as it is about not wanting to take the chance and have to spend for an analysis , and for oil, as I cannot afford to do both.

I thought typically when oil darkens it is from whatever additives, or detergents in the oil that are made to remove carbon deposits, other contaminants, and whatnot from inside the motor, and then carry that dirt to the oil filter?
Are you saying they put stuff in the oil to make it darken for no reason at all?
Do you have any links to what they add to them to make them darken from something other than what I mentioned?
Not doubting what you are stating, I would just like some more info to read about oil naturally darkening from other things than carbon deposits, and or contaminants.

Never said or implied they add stuff just to darken it intentionally but it darkens for the reasons you said when particles become suspended which means a detergent oil is doing it'* job. A non-detergent oil doesn't darken as quickly because it has no additives to break down the soot and carbon and let the oil carry it off. Here'* a link to a page that is well written and describes things we were talking about very well. I can't type that much..... http://www.nordicgroup.us/oil.htm#Th...k%20Oil%20Myth

As for the samples, here'* a page that has a sample analysis sheet and shows the many different metals and contaminants they read; Engine Oil Analysis - Bob is the Oil Guy - Bob is the Oil Guy It would take my one handed typing too long....LOL Bearings have copper alloys, tin and steel normally and then there are the valve stems, etc that all have various metals. I'm not now or ever have recommended an oil analysis on a regular basis. But just like my new Bonnie, I have records showing oil changes for it BUT I'm still gonna fill a sample bottle when I pull the oil tomorrow just for my own piece of mind on what is floating around in there. Just a comfort level for me to see if it shows low/normal readings or possibly something higher than normal to check out now just in case.