Value of a Replacement QT. & the 3 MONTH "Rule">?

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ULVER

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I have a older Crown Vic Police Interceptor, that uses about a quart of oil every couple weeks. Considering I always use a synthetic, and a REAL one at that (German Castrol), I usually go 6K for my OCI. I felt especially confident in this, because I felt that added quart of fresh oil, boosted the quality of the remaining 4 quarts. Sometimes I may go four or five months to get those six thousands miles.

Recently, I read a letter submitted to the two Italian brothers, who have the nationally syndicated newspaper column on car issues. It mirrored my situation exactly, and the writer was of the same mindset as myself. Except, he was trying this for 10K, with Dino oil.

The brothers quickly agreed, that he was asking for trouble. They said that replacing a single quart of oil, even several times over, before the next change, wasn't really bolstering the oil that was host to the new quart. Plus, you never want to keep oil in an engine longer than three months. They said that even if you are not at your suggested OCI, you need to change the oil after that amount of time.
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Mobil 1 has their new 15K oil. Amsoil talks about yearly oil changes. Royal Purple says you can go 12K with theirs.

So what really gives?
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IIRC, I saw a study where Mobil 1 was replaced per quart, as needed, to a car that was using as well. I believe adding a new quart when needed, allowed them to reach 16K on the fill, till the numbers started to show compromise.

I guess in this situation, comparing stynthetic to dino is like apples & oranges...

Thoughts welcomed......
 
I think I would switch to a High Mileage dino if I was adding a quart every couple weeks. That adds up. $5 per quart for Mobil 1 vs. $2.28 for HM.
 
If your car is using a quart every two weeks and you're driving 1,000 miles per week, it could be argued that your engine may be in less than perfect shape, and that perhaps your oil is getting crunked up by a messed-up engine.
Barring that though, really, topping off WILL rescue an engine's oil. The two brothers are like most other mechanics: mechanically competent, but not truly schooled in lubrication as an art or science.
 
If you do "severe service" driving (stop-and-go, cold weather, dusty) then 10k may be too long. If it's mostly highway miles, I think 10k is very achievable.

My Geo Metro eats a quart every 3 weeks. I fill up with cheapish dino oil. I change oil and filter every 6000 miles, about 6 months. Mostly highway driving. Over 100k miles and so far so good. I wouldn't use synthetic myself because it gets a bit pricey to keep topping up (and it's a Metro, not exactly a high performance car in need of maximum engine protection
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), but if I did, I would feel fine changing oil just once a year.
 
quote:
Plus, you never want to keep oil in an engine longer than three months. They said that even if you are not at your suggested OCI, you need to change the oil after that amount of time.
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That comment right there should tell you they have no idea what they are talking about. If they really said that then how can you trust anything else they say?
 
You are running $70 worth of premium synthetic motor oil IN ONE OIL CHANGE CYCLE through an old, worn out police car?


I believe I would be running nothing but the cheapest I could find on sale.


You are wasting some serious money.
 
quote:
Originally posted by michaelc80:

quote:
Plus, you never want to keep oil in an engine longer than three months. They said that even if you are not at your suggested OCI, you need to change the oil after that amount of time.
Click to expand...
That comment right there should tell you they have no idea what they are talking about. If they really said that then how can you trust anything else they say?
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Exactly. Was Mobil or Exxon sponsoring their column?
 
The Mariachi brothers are great comedians, and very good mechanics, but they are not oil experts. The 3-month rule is goofy. I have oil analsis reports showing good oil after many months. I use a 1-year rule and never have a bad report. Adding a quart of oil certainly replenishes the old oil as shown in many reports of folks using bypass filters.

In your old engine, I'd do an Auto-Rx cleaning. After that, I'd run either a 15W-40 oil or a high-mileage 10W-30 or 10W-40.


Ken
 
quote:
Originally posted by ULVER:
I have a older Crown Vic Police Interceptor, that uses about a quart of oil every couple weeks. Considering I always use a synthetic, and a REAL one at that (German Castrol), I usually go 6K for my OCI. I felt especially confident in this, because I felt that added quart of fresh oil, boosted the quality of the remaining 4 quarts. Sometimes I may go four or five months to get those six thousands miles.
Click to expand...
If I did the math correctly, you using a quart of oil every 600-750 miles? That implies that by 3K miles you added 4-5 quarts of oil? Assuming it's bad valve stem seals, I'd say that 6K miles between changes should be a breeze. With a good filter, or perhaps with only filter changes you probably could go quite a bit further. Do a UOA at 6K miles to prove it to yourself.

Using GC is this application is surely a waste. I'd use the least expensive SM/GF-4 10w30 I could find. The lowered ZDDP levels may extend the catalytic converter life too.

How hard is it to replace the valve stem seals on this engine?
 
Are these Italian brothers in Italy?

DINO oil isn’t a very descriptive term these days -- it could mean a Grp I or II based oil and there are huge differences between the two. In Europe, and particularly Asia and the rest of the world (outside Canada/US) Grp I basestocks are still predominate.

I would never try and run a Grp I based oil 10,000 miles. But a Grp II shouldn’t have any problem making that (depending on the type of service). In a severe service situation you could be stretching things out, but considering GM’s average OCI is 8500 miles with a conformable safety margin using their OLM, 10K miles should be doable.

I would say 6k miles for these new Grp II’s is relatively easy -- and you should just go to an off-the-shelf regular motor oil. I would be giving different advice somewhere else in the world like Asia where Grp I basestocks are used.

And 3month OCI’s! -- back in the 80’s when I was doing 3k/6 month OCI’s a friend told me he was doing 3k/3 months. And I thought I was being EXTRA cautious with my OCI. With a Grp II based oil, a 3 month OCI is cranking things up from GoofY.
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Gentlemen,
Are we talking about Click and Clack, the mechanic / comedians heard on your local NPR station?

If so, they recommend a 5,000 mile OCI. Nothing about 3 month changes. Frankly, what they are calling for is pretty standard thinking on BITOG. Here is a link and quote:
http://www.cartalk.com/content/features/Summer-Driving-Tips/change-oil.html

Our current recom mendation is to change your oil every 5,000 miles--though that number may decrease dramatically if Kendall delivers with that check they keep promising.

A word about hauling big loads in the summer: Most car manufacturers will recommend 5W30 or 10W30 oil year-round. However, your owner's manual may have a recommendation for what's called "severe duty," such as pulling a trailer. In this case, you might want to switch over to a higher-viscosity oil. Why? Well, under hot operating conditions, a thicker oil will thin out less quickly, making sure your engine stays well lubricated when it needs it most.

Signed,
Jett Rink in Bristol
 
Yes, these are the two bearded bozos that tend to be so vague and "safe" that they actually tell nothing that requires any substantial expertise ..and just general experience with being boned at the repair shop and basic mechanical understanding.

They'll never produce anything worth hearing that you don't already know.
 
With weak valve stem seals, that is exactly what HM oils are made for. GC may be great for an engine in perfect shape, but not one with such a problem. Even 10W-40 Syntec tended to burn up in my old BMW. My cat is now history (failed smog, high HC and NO with low CO) after that Syntec cycle. Watch out for cat and O2 sensor failure if you are burning a lot of oil.
 
At one time, over 20 years ago, the two brothers provided some very lucid and detailed advice on automotive repair and maintenance. Their knowledge on pre-1990 vehicles was particularly rich. But these guys are older mechanics who may not spin the wrenches anymore.

Things have changed since their early radio days and the laughs and wisecracks seem to have overshadowed things. Nevertheless, anyone who kept an early '60s slant six Dart as a daily runner into the late 1990s (when I stopped listening to them) is ok in my book.

The 3 month/3,000 mile standard was at one time the old-school mechanics rule. I'm sure the brothers were merely parroting the old rule from their younger days. I know many current mechanics who still blindly follow it. Most mechanics don't know motor oil. I know of one young tech asking a senior one what kind of oil a particular MB diesel required, and was told "the slippery kind".

But more importantly, the brothers gave the SAFE answer. I would be leery of advising in a national publication to run dino for 10K without qualification. These guys are smart enough to know that, too.
 
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