What makes severe duty severe?

[RamFan]

To be honest no one will have an answer unless you're an engineer on the inside but that doesn't stop us from speculating like we always do.

Vehicles come with regular and severe service maintenance intervals, most notably increased oil change intervals and transmission fluid intervals are what is commonly prescribed for severe over regular duty.

However, I've noticed that some car makers are doing away with severe or regular maintenance schedules and prescribing only one schedule. Chrysler instantly comes to mind. GM prescribes OLM based maintenance and I believe Toyota prescribes one schedule as well. I haven't checked on the other makers. On my charger for instance under severe duty I'm supposed to do tranny fluid changes every 60k miles and gear oil changes every 48k miles. Under normal duty it calls for NO tranny or gear oil changes. However starting in '08 Chrysler did away with two schedules and stuck in a simple 6k/6mo schedule.

I think this tells us that car makers aren't prescribing normal or severe duty based on equipment tolerance but more so on what they think the lubricants used with that equipment can tolerate. As lubricants of all kinds have gotten increasingly better with time, car makers are now comfortable relaxing/extending maintenance procedure and/or not differentiating between severe or normal duty.

I believe that what was once deemed severe duty (Multiple cold starts, sub 10 mile trips, extensive idle, etc.) was decided majorly because of the limitations of lubricants at that time not what the equipment could handle. Due to the increased level of lubricant performance I feel as though the severe duty of yesterday is today's normal duty.

What do you think?

 

[ARCOgraphite]

Short trips without the engine warming will kill modern oil in a new car in short order. PCV are better/tighter, warmup to lightoff (closed loop) faster but still not good enough to overcome a short tripper. I recommend quarterly/seasonal OCI on short trippers, yeah.

 

[Corvette Owner]

Crazy post. It's a fact that oil is better today. Use of OLMs make the severe/normal use obsolete. Cars that don't use an OLM still define severe/normal use. I think you know why the severe use factors are severe.

 

[morris]

i have had a few new chrysler cars/trucks. the severe service maintenance intervals, rating will be hard to meet if you live on pavement, in town. to me use zinc in oil, and i like a little, just a little thicker than called for. change oil 3,000 miles, and of course the filter, but NOT Fram. i check the factory SERVICE MANUAL, i dont even look at the operators manual.

 

[RamFan]

Originally Posted By: Corvette Owner
Cars that don't use an OLM still define severe/normal use.


Not true. Using my mom's '08 Sebring as an example. She's got EVIC, she's had the vehicle since new and it has never displayed the "oil change needed" message nor has the "oil change" light come on. All maintenance has been done by me and I've never attempted to reset the message or light since its never come on. I looked at the manual and it only gives one schedule, 6k/6 months. No severe duty no regular duty schedule. Just an "If EVIC doesn't display, follow this schedule" schedule.

 

[Rock_Hudstone]

Originally Posted By: Corvette Owner
Crazy post. It's a fact that oil is better today. Use of OLMs make the severe/normal use obsolete.

Synthetics and special blends aside, is the average motor oil really that much better than it was say 15 years ago? Seems to me the VOAs show each new grade to be weaker than the one before.

I think it has more to due with cleaner running modern engines and a lot of pandering to the Save the Planet green crowd that is behind much of the push for extended oil change intervals.

 

[Corvette Owner]

Originally Posted By: RamFan
Originally Posted By: Corvette Owner
Cars that don't use an OLM still define severe/normal use.


Not true. Using my mom's '08 Sebring as an example. She's got EVIC, she's had the vehicle since new and it has never displayed the "oil change needed" message nor has the "oil change" light come on. All maintenance has been done by me and I've never attempted to reset the message or light since its never come on. I looked at the manual and it only gives one schedule, 6k/6 months. No severe duty no regular duty schedule. Just an "If EVIC doesn't display, follow this schedule" schedule.



So, if the EVIC displays it is severe service. 6K/6 months is normal service.