Older cars = shorter oil change intervals, why?
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The 1993 E36 Bimmer of mine calls for 7,500mi (about 12,000km), as did the E30 generation prior. Both have the Service Indicator system which can theoretically vary the OCI by some extent. As far as I've seen, its only a few hundred kilometres variation.
At least in 1993, you were looking at API SG oil carrying the CCMC-G5 rating. Today we have API SN and ACEA A3/B4. In theory even a 15w40 conventional is vastly superior to many oils from that era.
As for Toyota Camry in the 1990s, the OCI was pushed out to the same as my BMW. The internet is full of claims this caused the "sludge crisis" in the 1MZ-FE V6, and the 5S-FE.
On the other hand, a 1975 Holden Monaro with the Holden 253 V8 calls for the "old fashioned" 3months/3k miles (5k km) OCI on anything from 10w30, to 20w40 or even 20w50. I'm sure comparable vehicles in the USA would've been spec'd longer at the time.
At least in 1993, you were looking at API SG oil carrying the CCMC-G5 rating. Today we have API SN and ACEA A3/B4. In theory even a 15w40 conventional is vastly superior to many oils from that era.
As for Toyota Camry in the 1990s, the OCI was pushed out to the same as my BMW. The internet is full of claims this caused the "sludge crisis" in the 1MZ-FE V6, and the 5S-FE.
On the other hand, a 1975 Holden Monaro with the Holden 253 V8 calls for the "old fashioned" 3months/3k miles (5k km) OCI on anything from 10w30, to 20w40 or even 20w50. I'm sure comparable vehicles in the USA would've been spec'd longer at the time.
All the cars I remember from the late 80s to the mid 90s called for a 7500 mile/6 month normal and 3000 mile/3 month severe duty OCI. I think API SG was the standard when I started driving a 1989 Acura Integra RS, but the owner's manual always allowed for the use of the previous standard.
Some have longer intervals, but others use OCI electronics which are theoretically more accurate than a blanket round number. Heck - my wife's 2002 Honda Civic had a recommended 10K miles/1 year normal OCI on API SJ 5W-20. If they upped the OCI, I'm thinking it had more to do with the quality of the oil and what the engine would (or wouldn't) do to the oil.
Some have longer intervals, but others use OCI electronics which are theoretically more accurate than a blanket round number. Heck - my wife's 2002 Honda Civic had a recommended 10K miles/1 year normal OCI on API SJ 5W-20. If they upped the OCI, I'm thinking it had more to do with the quality of the oil and what the engine would (or wouldn't) do to the oil.
Originally Posted By: CR94
Originally Posted By: BrocLuno
Well, 15,000 km is still roughly only 7,500 miles and that is entirely within the range of todays best dino and most synthetics. ...
Did you mean roughly only 9,500 miles? (9321, to be more exact)
At least in the US, car manufacturers approved change intervals well over 5k-7k long before the 90s. It was 7500 miles [about 12,000 km] for my 1981 Mazda, and that wasn't new or extreme then.
I said roughly. I just do 2:1 for ease. I know it's closer 1.7:1 for somewhat more critical estimates, but the idea was to see if more than 3K miles was involved...
I also think of the 1990's as newer. The idea that if it has an oil bath air cleaner is one I had not thought of though
But, I'm really more a kind of 'if it's a 6 volt system, it's old' kinda guy.
Geez, my wife's 1997 Jag is sequential port and 4 valves per cylinder and that's new enough for me ...
I'm still mostly building push-rod motors with carbs, and running 32:1 2-strokes ...
Originally Posted By: BrocLuno
Well, 15,000 km is still roughly only 7,500 miles and that is entirely within the range of todays best dino and most synthetics. ...
Did you mean roughly only 9,500 miles? (9321, to be more exact)
At least in the US, car manufacturers approved change intervals well over 5k-7k long before the 90s. It was 7500 miles [about 12,000 km] for my 1981 Mazda, and that wasn't new or extreme then.
I said roughly. I just do 2:1 for ease. I know it's closer 1.7:1 for somewhat more critical estimates, but the idea was to see if more than 3K miles was involved...
I also think of the 1990's as newer. The idea that if it has an oil bath air cleaner is one I had not thought of though
But, I'm really more a kind of 'if it's a 6 volt system, it's old' kinda guy.
Geez, my wife's 1997 Jag is sequential port and 4 valves per cylinder and that's new enough for me ...
I'm still mostly building push-rod motors with carbs, and running 32:1 2-strokes ...
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Originally Posted By: PimTac
... My definition of old; if it has a oil bath air cleaner, it's old.
If an oil bath air cleaner was option (over the standard-issue crude screen or mesh, oily or not), it's older.
So far, no one has mentioned big changes of the 60s and 70s that made oil's life easier:
1) PCV systems (vs. draft tubes or systems that directed blowby to the intake, but lacked fresh-air intake)
2) Unleaded fuel, and
3) Tightened control of fuel mixture, even with carburetors.
... My definition of old; if it has a oil bath air cleaner, it's old.
If an oil bath air cleaner was option (over the standard-issue crude screen or mesh, oily or not), it's older.
So far, no one has mentioned big changes of the 60s and 70s that made oil's life easier:
1) PCV systems (vs. draft tubes or systems that directed blowby to the intake, but lacked fresh-air intake)
2) Unleaded fuel, and
3) Tightened control of fuel mixture, even with carburetors.
It's a combination of things mostly mentioned above.
Leaded fuel went away, fuel injection became common as did higher energy ignition systems.
It also isn't so much a matter of engine oils having really improved, it's rather that a variety of industry and maker's certs have evolved to identify those oils suited to longer drains, which have in turn eliminated many of the more rudimentary formulations from the market.
tig's decades of 10K drains on M1 illustrate this. Those 10K drains wouldn't have worked as well with most of the oils available in 1978 and there were no widely accepted certs that would have helped in identifying suitable oils.
This was an era in which Mercedes still recommended oils by brand and trade name, for example and BMW OMs said that you should see your dealer for recommendations of what were called "special oils".
Also, recommended drain intervals were typically very conservative, so manufacturer's had room to open up the envelope on drain intervals.
Leaded fuel went away, fuel injection became common as did higher energy ignition systems.
It also isn't so much a matter of engine oils having really improved, it's rather that a variety of industry and maker's certs have evolved to identify those oils suited to longer drains, which have in turn eliminated many of the more rudimentary formulations from the market.
tig's decades of 10K drains on M1 illustrate this. Those 10K drains wouldn't have worked as well with most of the oils available in 1978 and there were no widely accepted certs that would have helped in identifying suitable oils.
This was an era in which Mercedes still recommended oils by brand and trade name, for example and BMW OMs said that you should see your dealer for recommendations of what were called "special oils".
Also, recommended drain intervals were typically very conservative, so manufacturer's had room to open up the envelope on drain intervals.
I'd be okay doing 6,000 miles in my MG, but I usually don't because I don't want it sitting over the winter with dirty oil in the crank case.
It's an old sloppy tractor engine with a decent amount of blow-by. I run it a bit on the rich side, which is where SUs tend to perform better and my engine is happier(plus it keeps the notoriously problematic exhaust valves a bit cooler), but it also means that I get more fuel dilution.
I run a 195º T-stat all around and my engine comes up to temp quickly(it always amazes me how long it takes one with neglected maintenance to warm up-I advocate changing the T-stat if its age is unknown as I suspect a lot of the cold blooded cars have "leaky" t-stats) but the overkill oil cooler on it tends to keep the oil temps in the 180-190º range. The oil only starts to get up to optimum temperatures(and temperatures where it will efficiently cook off fuel and water) with long drives.
It's an old sloppy tractor engine with a decent amount of blow-by. I run it a bit on the rich side, which is where SUs tend to perform better and my engine is happier(plus it keeps the notoriously problematic exhaust valves a bit cooler), but it also means that I get more fuel dilution.
I run a 195º T-stat all around and my engine comes up to temp quickly(it always amazes me how long it takes one with neglected maintenance to warm up-I advocate changing the T-stat if its age is unknown as I suspect a lot of the cold blooded cars have "leaky" t-stats) but the overkill oil cooler on it tends to keep the oil temps in the 180-190º range. The oil only starts to get up to optimum temperatures(and temperatures where it will efficiently cook off fuel and water) with long drives.
Well I actually ended up getting a 2003 Camry with the 4 cylinder 2ZA-FE which calls for 15,000km intervals under normal conditions or 7,500km under sever driving conditions. Knowing this, I now feel pretty safe with 15,000km intervals running a quality synthetic. Please correct me if I am wrong
That depends entirely on your driving conditions.
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