Oil change without filter change.

Stallingrad

Just a hypothetical question. If a car has oil and filter changed once every two years, but one would change JUST the oil two or three times between those dates, is there any harm in this?

I realise without changing the filter you are not changing all the oil, but is adding 90% new oil to old oil going to do any harm between the bi-annual filter change.

It is very easy to change just the oil as I have suction pump, and I don't want to get into changing the oil filter, or jacking up the car to get to the sump.

Alanstrainor

It's rare that you'll be able to get 100% of the old oil out of an engine at a typical oil change anyway. So I wouldn't think there's a huge issue in changing the oil without changing the filter. But at the same time, if the filter is easily and cheaply changed then I would be inclined to do it every time you change the oil.

I don't particularly like the idea of 2 year oil changes too. In my mind this is a marketing gimmick by manufacturers to appeal to companies leasing large amounts cars who look to save on servicing costs. Annual servicing with both air and oil filter changes would be best practise in my opinion. Oil filters are generally very cheap anyway.

corks finest

Stallingrad wrote: »

Just a hypothetical question. If a car has oil and filter changed once every two years, but one would change JUST the oil two or three times between those dates, is there any harm in this?

I realise without changing the filter you are not changing all the oil, but is adding 90% new oil to old oil going to do any harm between the bi-annual filter change.

It is very easy to change just the oil as I have suction pump, and I don't want to get into changing the oil filter, or jacking up the car to get to the sump.

I change filter every second service,use a sealey vac pump for oil and CVT oil removal , measure it and find most oil is withdrew,2 nd service, remove filters etc,and flush engine

SweetCaliber

It's not that not changing the filter would leave old oil in the engine, as Alanstrainor said above even when you drain the engine and remove the filter your not going to get 100% of the old oil out of the engine.

However, an oil filter can get dirty and clogged with debris over time. Considering the filter is the main flow of oil if it becomes clogged it can restrict the flow of oil. An oil filter isn't expensive, considering that not changing it and the greater cost it could leave you with down the line I think its best to change it when changing the oil.

CJhaughey

The issue is that by design a filter has a bypass built in, this usually takes the form of a spring that allows the filter material to lift if pressure builds up within the filter due to clogging of the material.
This is not visible but it will mean the engine is running with no filter as the oil is simply circulated around the filter and bypassing the media.
If anyone thinks a biennial oil change is a good idea then its probably futile trying to explain why the filter should also be changed.

corks finest

Change mine every 6/ 9 months

dooroy

If anyone thinks a biennial oil change is a good idea then its probably futile trying to explain why the filter should also be changed.
Today 13:27.

Agree completely - I can never understand why people pay big money for a car and then , sometimes , use cheap oil and want to leave the filter (and all the crud it has collected ) to contaminate the fresh oil immediately , plus as you say, the possibility of unfiltered oil circulating and no obvious effects until engine develops problems.

corks finest

dooroy wrote: »

If anyone thinks a biennial oil change is a good idea then its probably futile trying to explain why the filter should also be changed.
Today 13:27.

Agree completely - I can never understand why people pay big money for a car and then , sometimes , use cheap oil and want to leave the filter (and all the crud it has collected ) to contaminate the fresh oil immediately , plus as you say, the possibility of unfiltered oil circulating and no obvious effects until engine develops problems.

AFAIK recommended to change filter ever other service ( coming from a hybrid ,now a normal petrol automatic

corks finest

dooroy wrote: »

If anyone thinks a biennial oil change is a good idea then its probably futile trying to explain why the filter should also be changed.
Today 13:27.

Agree completely - I can never understand why people pay big money for a car and then , sometimes , use cheap oil and want to leave the filter (and all the crud it has collected ) to contaminate the fresh oil immediately , plus as you say, the possibility of unfiltered oil circulating and no obvious effects until engine develops problems.

AFAIK recommended to change filter ever other service ( coming from a hybrid ,now a normal petrol automatic,and as I change mine max 9 months I'm well within any recommendation

Big Nasty

I'd be more likely to change the filter twice for every oil change.

SweetCaliber

CJhaughey wrote: »

The issue is that by design a filter has a bypass built in, this usually takes the form of a spring that allows the filter material to lift if pressure builds up within the filter due to clogging of the material.
This is not visible but it will mean the engine is running with no filter as the oil is simply circulated around the filter and bypassing the media.
If anyone thinks a biennial oil change is a good idea then its probably futile trying to explain why the filter should also be changed.

Does the bypass only apply to screw on filters or does it also apply to the drop in ones (for example VW, filter goes into housing and cap screws back on) aswell?

Eric Cartman

Regardless of what fancy marketing words a manufacturer wants to use , the mileage you do etc... I believe the oil and oil filter should definitely be changed annually , I haven't ever seen an oil filter thats over 50 euro , even on older luxury cars (7 series etc...) they're 20 quid for a really high end one.

Theres just too much of a chance of the filter clogging, filter media depleting, a seal going etc.... Even if you do 2,000km a year , get the filter and oil changed annually (or more than annually if you do higher mileage, I don't believe in these 25,000km service intervals either)

Even beyond engine health, as a private buyer or a dealer taking a trade in is going to hammer you on price if the car hasn't got the right amount of services for its age/mileage.

CJhaughey

SweetCaliber wrote: »

Does the bypass only apply to screw on filters or does it also apply to the drop in ones (for example VW, filter goes into housing and cap screws back on) aswell?

Cartridge type filter elements are just a filter, the bypass will usually be in the filter housing somewhere.
Screw on type have a spring in the metal case somewhere, either top or bottom.

Oil doesn't just get dirty from carbon it also holds acids from combustion and will acidify over time, that's why an oil change is specified for both time and milage.

corks finest

CJhaughey wrote: »

SweetCaliber wrote: »

Does the bypass only apply to screw on filters or does it also apply to the drop in ones (for example VW, filter goes into housing and cap screws back on) aswell?

Cartridge type filter elements are just a filter, the bypass will usually be in the filter housing somewhere.
Screw on type have a spring in the metal case somewhere, either top or bottom.

Oil doesn't just get dirty from carbon it also holds acids from combustion and will acidify over time, that's why an oil change is specified for both time and milage.

This place is a mine of information

Stallingrad

Great advice, thanks everyone.

Tommyboy40

I have always changed oil and filter every 6000 miles. Filter is less than €10. Mercedes CL500

stimpson

I used to be on a car owners group and one of the guys was a chemical engineer for BP. He wrote a long primer on oil and the take away of it all was:

Genuine filter, oil that meets spec (even if it’s not brand name) and change annually at least. The single thing you can do to increase the lifespan of your engine is to increase the frequency of changes.

Truckermal

OP next time you shower keep wearing the same socks and underpants....It's the same thing as not changing the filter.