Based on some posts I decided I'd try the Castrol Synthetic Blend motor oil for my next change, but it doesn't say how long it is good for. I've seen anything from 6k to much more posted, does anyone have solid info on how long it can be left in between changes?

 

What is your driving style and are you doing short trips or highway driving?

 

the way i look at it, if your owner's manual says you can do 7k miles for "normal" service, you can hit that with dyno.....so i'm sure you can hit that with synthetic.

hell, my 1992 Galant says 7.5k miles way back then with that crappy oil....today's oils are so much better, so i go 9k on dino....why not?

 

you dont change oul because it is worn out, you change it because it gets dirty, fuel contaminated, carbon buildup, etc. if you put synthetic in a truch and drive cross country and back, thats probably o.k. If you drive on country roads or dusty conditions or mud racing, etc. you are much better off to put Super Tec from Wal Mart and change it every 3 months or 5000 miles. Remember, when you change oil, it is normally not out of lube spec, it is just dirty..

 

Yup Steve is completely right. I work as a Lube tech at a dealership and I change mine every 3,000miles. I see people come in all the time after going 8-10k miles and the oil looks absolutely horrible. You might also look for a top quality filter. The filter has as much or more to do with it than the oil itself. Wix makes a pretty good filter.

 

So, if I changed my filter every 2k, would my oil last longer? And, are you saying the true way to determine when I should change my oil is by how it looks on the dipstick? Nice carmel color and I keep going, chocolate sauce color and I change it? I was always under the impression you changed it because it broke down - like the commercial says "thermal breakdown" - after a certain amount of time.

BTW, I generally drive rural blacktop or highway miles. Very little dirt roads. But the pollen here in NC will turn your car yellow overnight.

 

Keep changing it at the same interval because as stated before, it gets dirty at the same rate.

I just do mine every 5K. Motorcraft 5w20 with Motorcraft filter.

Mike

 

i do 5000 intervals because its easy to keep track on the odometer. been doing it that way for 30 years on everything i own. i use mostly FRAM filters which some will knock, but i dont have problems. I use Havoline 5 w 30 in the two newer trucks, but use Wal Mart Super Tech 10w 40 in the older trucks, tractors, lawn mower, etc.

 

I wouldnt run the oil any longer than 5,000 miles. I personally dont agree with the notion that with synthetic oil you can run the oil longer.
Synthetic or not, oil still gets dirty and you need to change the oil often in order to drain that dirt out of your engine.

 

what everone has posted is sorta right but remember a syn blend is not at this point in time any better than a "normal" oil, they both contain a small amount of syn base oil.

A syn blend is a marketing deal only there is NO recomended amount of syn to call the oil a "blend" when in fact most all SM spec oils now days are a syn blend in that normally they need a small amount of PAO of GPIII to qualify.

Buy a full on syn like Mobil 1 or Redline and go 10K or use whatever brand you can get cheap, oil gets dirty it is ment to.

How far to go get a UOA done any other recomendation is just that.

IMHO ANY quality SM oil will go 5-6K easy 3K drians are a waste of time.

bruce

 

Question! What do you expect to see as a difference by changing oil brands?
If you were using 5w20 Motor Craft Blend from the start, at 5k intervals you would not he here asking.
You can't tell anything about oil by just looking at it unless you didn't change it for 10k miles and just kept adding oil.
The oil is a blend of additives as a package. Some are extremes pressure additives, some detergent to keep the motor clean and the carbon in suspension which is the brown/black you see. It's normal and you cannot tell when it's loaded with to much. That's why you change filter and oil at reasonable intervals.
The filter does not clean carbon from the oil because the micron size is to small for the filter medium nearly all the time.
Extended intervals cause an increase in viscosity by the loading the oil gets from contaminates as well as depletion of parts of the additive package.
Why people insist on getting so **** about oil instead of changing it and the filter inside the reccomended intervals, is quite amusing.
You don't need any more info that what I just ran thru.
Go to a Wal Mart and get your Motorcraft oil for about $2.30 a qt and a Motorcraft filter change at 5 ot 6k and be done with it.
By the way, I am coming up on 100k all on MC 5w20 for heavey towing and every day use and the motor sounds and runs like it was new and will be towing again at nearly 12,000 lbs gross combined weight. Only problem over this time was a bad COP around 55k miles.

 

Answer: I didn't really know that much about oil so I appreciate all the posts. I was under the impression that oil "broke down" at some point and lost this thing called "viscosity". Seemed to me that "viscosity" meant the oil's ability to stay together chemically and lubricate things as it is supposed to. So, in my uneducated mind it seemed that a synthetic blend motor oil would stay together chemically better - for some unknown reason to me, mostly just 'cause it sounds like it would - and therefore protect my beloved 5.4L engine better.

I've had the truck since it had 100k on it - now up to 112k - and have been changing every 4k in an attempt to prolong life and split the difference between what seemed like a "short" change of 3k and a "long" change of 5k. By buying the synthetic blend and thinkig it would last longer I thought it might provide a bit of savings too - thinking it might go 7k between changes and at only a buck more a quart save me some cash while doing a better job.

So, now I have learned:
1. Oil is only changed because it is dirty - NOT because it wears out. That's good fundamental understanding that at 41 no one has ever said to me before.

2. All the modern oils have a syntheitc blend of some sort so the whole "synthetic" thing is just good advertising for those of us not knowing the difference.

3. I'll stick with my Castrol 5w20 (grey top) motor oil, my Motorcraft filter, and my 4k interval (might as well err on the side of caution - plus I seldom hit it on the low side of 4k anyway) and be done with it.

Thanks for all the information. As always, this site is a great place to learn.