Long change synthetic or short change regular?

[kbohip]

I have an '03 Jeep Grand Cherokee with the 4.7HO V8 in it. I've ALWAYS changed the oil in my cars at 3k miles no matter what, even with synthetic. I'm using 5W-30 Mobil 1 in it now and since it was 6k miles old.

My question to you guys is this. Is it better to go with 3k mile change intervals with regular oil or 6k mile intervals with synthetic? Everyone claims that 3k mile change intervals with synthetic is a total waste of money but I can't really see how going 6k miles on synthetic would be better than just putting in fresh regular oil every 3k miles instead.

I had planned to do an oil analysis at 3k miles with my current synthetic oil but at $30 I may as well just put in clean oil. Would I be ok going 6k miles and doing the analysis then?

PS, I searched for a topic like this and didn't find anything similar.

 

[Ugly3]

kbohip - My question to you guys is this. Is it better to go with 3k mile change intervals with regular oil or 6k mile intervals with synthetic? Everyone claims that 3k mile change intervals with synthetic is a total waste of money but I can't really see how going 6k miles on synthetic would be better than just putting in fresh regular oil every 3k miles instead.

It is cheaper (in terms of oil change cost) to use any API certified SL rated oil and change it every 3,000 miles.

It is better for the engine to run a quality full synthetic oil 6,000 miles between changes (using your two alternate change intervals). Why is this better you ask? Bacause the wear rate per 1000 miles is greatest in the first 3,000 miles of oil use and goes down per 1000 miles until the oil dies.

That said - from the data I have seen a quality conventional oil can safely be run 5,000 miles and synthetics can safely be run into the 7,000 mile to 10,000 mile range, depending on driving habits and engine charactoristics.

If you are doing 2 mile trips to the 7/11 stay on the short side. If you drive 60 miles a day on the freeway the longer intervals are a snap.

I drive 25,000 to 30,000 miles a year (Chrysler 3800 V6) and change my full synthetic every 10,000 miles. Been doing this since 1994 with no problems.

 

[Al]

quote:

---

Originally posted by Ugly3:
Bacause the wear rate per 1000 miles is greatest in the first 3,000 miles of oil use and goes down per 1000 miles until the oil dies.

---

That information you are citing is from an SAE publication. It was not that straight forward and as cut and dried as I recall. The wear products dropped off but that really can't be correlated in changing patterns of wear. Also I seem to recall that the population study was not really statistically valid. I really wouldn't hang my hat on it.

I think the choice between dino and synthetic is getting to be much more of a personal choice. Dino oils are closing the gap in terms of benefits compared to syn.

I would say 6K miles would be O.K. for an analysis. The other advantage though by doing an analysis is to spon coolant leaks, fuel dilution, high insolubles and air filter lekage. So just bc you go 3K miles doesn't mean an oil analysis is un-necessary.

 

[Ugly3]

Al - That information you are citing is from an SAE publication. It was not that straight forward and as cut and dried as I recall. The wear products dropped off but that really can't be correlated in changing patterns of wear. Also I seem to recall that the population study was not really statistically valid. I really wouldn't hang my hat on it.

Actually my info comes from the SAE study and the current long life synthetic oil tests currently being conducted at Paradise Garage. Both pieces of data suggest the same thing, wear per 1000 miles decreases after the oil has been run 3,000 miles.

Here is the link:
Paradise Garage

 

[michaelc80]

You have to factor in how quickly you put the miles on it. If I did 3K changes, I'd be under my vehicles once every couple months. With 5-7K OCI's I don't have to spend as much time under it, but I still get the protection I need.

 

[T-Keith]

I don't think we really know how much of the wear particles that show up in the first 1000 miles are due to actual wear occurring or particles being picked up by the new oil and it's fresh additive package.

Looking at all the UOA, it seems that unless you are hard on your vehicle, a good dino oil changed at 3k or even 5k miles is hard to beat. Depending on the car a 6k synthetic might get you a little less wear, but not a lot.

-T

 

[47HO]

kbohip,
I'm currently running the Amsoil 10W-30(ATM) in my '02 GC with the same engine as yours. I'm doing a one year interval, although I average only about 12,000 miles per year. I have done a UOA on the XL-7500 in 10w-30, it is posted here . It would be great to see another UOA on this motor from someone else!

BTW, did DC change the recommended oil weight for the 4.7 HO? In '02, they specifically stated to use 10W-30 in this version of the V8.

 

[Blue99]

quote:

---

I really wouldn't hang my hat on it.

---

I tend to agree with Al on this one. In 3MP's study, the higher amounts of UOA wear metals in the first 3,000 miles may not be directly correlated to the performance of the oil.

Whether it's an anomaly generated by the sampling & testing method, a dispersant function of the oil, flow of contaminants in the oil stream, or an additive quirk, a satisfactory explanation has not yet surfaced.

 

[kbohip]

quote:

---

Originally posted by 47HO:
kbohip,
I'm currently running the Amsoil 10W-30(ATM) in my '02 GC with the same engine as yours. I'm doing a one year interval, although I average only about 12,000 miles per year. I have done a UOA on the XL-7500 in 10w-30, it is posted here . It would be great to see another UOA on this motor from someone else!

BTW, did DC change the recommended oil weight for the 4.7 HO? In '02, they specifically stated to use 10W-30 in this version of the V8.

---

I just checked my owner's manual and it says 5W-30 recommended for the 4.7 and 4.7HO engines. It doesn't give any special recommendation for the HO, but it also says 10W-30 is acceptable down to 0 F*.

I should also add that most all of my driving is city stoplight to stoplight style. I very rarely am on the highway much with it. Most of my trips (work commute) are about 25 minutes each way but only 7 miles long. I average almost 1,000 miles a month usually.

I think I will run it to a 6k mile change interval this time through and then get an anlysis done.

BTW, this forum is excellent! Seldom do you find such knowledgeable people anymore in a forum such as this.

 

[RedWolf4000]

Im not a chemist, but if oil appeared to show less wear after its first 3000 miles, wouldnt that mean its becomming saturated?

(I may be wrong) but doesnt oil become saturated when it suspends dirt and wear particles? If this is true, wouldnt it make sense to see less wear in the engine after 3k, even though there actually is the same or more wear going on, but the oil just doesnt do its job of picking it up to show in the report??

Please correct me lol.

 

[Robbie Alexander]

quote:

---

Originally posted by kbohip:
My question to you guys is this. Is it better to go with 3k mile change intervals with regular oil or 6k mile intervals with synthetic

---

Application? Goals? Worry/Fears? Desire?

In general with normal people using normal applications... I'll venture on a LIMB and
Say the protection will be more than fine using
any Dino out there rated Sj or Sl depending on needs. Hint: it will/Should go several hundred K before you should/need to think about worry... Life happens, nothing is set into stone, but a good dino and a flush from time to time if needed or desired IMO would get most people in most applications of "normal folk" commutes....
Now, just don't try to pull a 7000# boat in a pinto..... okay

 

[Audi Junkie]

quote:

---

In 3MP's study, the higher amounts of UOA wear metals in the first 3,000 miles may not be directly correlated to the performance of the oil.

Whether it's an anomaly generated by the sampling & testing method, a dispersant function of the oil, flow of contaminants in the oil stream, or an additive quirk, a satisfactory explanation has not yet surfaced.

---

I thought it was simply that, during the initial test, the engine was still breaking-in.

Economicly, I can buy 2 fills of an oil like Motorcraft and 2 filters for the price of 1 fill of Mobil1 and 1 filter.

imo, the physical process of draining and filtering contaminates out twice as often cannot be matched by a single fill of Mobil 1.

Understandably, a really bad dino oil will have problems, but new conventionally-priced oils seem much better. Say, 2500 miles on Motorcraft or Havoline verses 5000 miles on Mobil 1??? I'd take 2 fills of M/C.

 

[Mamala Bay]

Motorcraft might just have something here too...Them synthetic/blend is something to consider...good wear and stable.

 

[OffOrWFO]

Don't forget that other things need to be serviced too. Tires need rotated on my truck at 5K and things need greased too. 5K on syn costs a little more (assuming filters cost the same) but it matches my other service intervals so it works for me. If you pay to have your oil changed then you don't have to run twice as long to pay for syn.

 

[BlueOvalFitter]

What do ya'll suggest if I use a blend of 3 quarts 10W30 Mobil1 and 3 quarts Chevron Supreme 10W30 dino?

 

[Dr. T]

It's my understanding that conv. oils will begin deposits immediately and will eventually lead to greater deposits than synthetics...even @3k OCI's...true?

 

[Alan]

I used to think that too but seeing a couple of pics on the board that showed clean internals using dino(especially the 3.1L with 300K miles)has changed my mind

.

The new dino's are better than ever

!

 

[SWS]

There are a lot of good comments above! Additional reasoning for using Synth instead of conventional oil:

1) Better cold flow. Mobil claims that M1 flows 5X - 6X faster than conventional oil on start-up. This is important to me since I am a in-town, short-trip, stop-and-go driver.

2) Better thermal margin. Synth is claimed not to break-down under heat stress. I have a hot-headed '97 Camry (Sludge Motor), and having recently switched to Synth at 65K miles, I observe that the Synth still looks like new after a summer of driving - the conventional oil I used previously (Pennzoil 10W-30) turned dark rather quickly in previous summers, using 3K mile / 3 month OCI. Granted, not a scientific study, but I have always changed the oil myself and was surprised that the conventional oil looked worse in the summer than in the winter on this car.

 

[newtoncd8]

I observe that the Synth still looks like new after a summer of driving - the conventional oil I used previously (Pennzoil 10W-30) turned dark rather quickly in previous summers


I always thought you wanted the oil to get dark because that meant it was doing its job. In other words, the oil is holding the by-products in suspension until it is drained out.

 

[Geoff]

I have been a long time Mobil 1 user with OCIs at 3-4K miles. I now think that conventional oils (say Group II oils) have closed the gap to the point that it makes much less difference. Review the used oil analyses and be your own judge. Personally I like changing more often to shed fuel and other pollutants from the oil, depending on use, engine age, and engine design.