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Thread ID: 118452	2011-06-05 05:58:00	Car's oil changes ...	Nomad (952)	PC World Chat

Post ID	Timestamp	Content	User
1207160	2011-06-06 10:50:00	I'm not sure I follow your reasoning, if you mean the time it takes to fill an empty filter and for the oil light to come on, then yes, a bigger filter can will take slightly longer to fill than a smaller cannister, meaning bearings are without pressure feed for a slightly longer time. If one is worried about that, then the filter could be partially pre-filled. Unless things have changed radically since I used to work in hydraulics and filtration, then car filters generally have a nominal rating of around 25 to 35 micron. Some will be better made than others, some poorly made ones may leak around the bypass valve, and the filter media may be of poorer quality, all you can do is to buy well known brands and hope for the best. All things being equal the bigger the filter area the longer it will last, a bigger area certainly will not cause reduced flow. However, 30 micron is way bigger than minimum oil film thicknesses in bearings, and car filters don't really remove much of the fine particles that can cause wear. A magnetic drain plug is a good thing. A filter rated at an absolute level corresponding to minimum oil film thickness, say 1 micron or less, would block up in very short order. My old A40 Somerset didn't filter the main oil flow, it had a bypass filter which just filtered a small proportion of the flow and returned it to the sump, whilst my Ariel Square Four just had a coarse wire mesh strainer :) My E93A was the same it had no oil filter as standard although after market ones were available in NZ. My model A was the same just a whitebait netting looking screen on the oil pump pickup. The E93A not only had no oil filter it had no oil pressure gauge or light. So the only oil pressure indication you had was the big ends starting to knock. I lost an E93A engine on first test run because a bit of gasket sealant had blocked the oil passage where it came up by the a side plate. Which was a horrible pain in the arse because they were poured bearings. Hard case my Ford Trader SL engine has 2 oil filters one filters the bypassed oil.	prefect (6291)
1207161	2011-06-06 10:57:00	cygnusx1.net Last picture down (the 7mgte) Doesn't look that bad in the picture but it really is a **** to get out - and near impossible to do without spilling it. Edit: See here: i63.photobucket.com	--Wolf-- (128)
1207162	2011-06-06 11:02:00	Yes shoulda wrenched it out with a screwdriver! Dad recalled that's what our mechanic said one day but why didn't he go that way :D Just when he has the time, won't cost us for him to loosen it...	Nomad (952)
1207163	2011-06-06 13:05:00	Mech shop for me. Normal service routine. Havent got time anymore to much on car except the usual checks.	rob_on_guitar (4196)
1207164	2011-06-06 16:27:00	I see that the concept of flow-rates and such of the filter still raises it's head in Upsidedown Land - prolly here in the US too to anyone who's not familiar with the flow design of the modern engine . (I wanted to post a pix or two about here - but the drawings that I can Google are either very crude and don't have all the devices in the artwork, or are so complicated that they are impossible for an engineering student to decipher . Hence - no pictures . ) The problem with an un-charged/fresh-empty oil filter at start-up are many - but most aren't decidedly dangerous or even hazardous to the engine anyway . Like the rules of English Language, there are exceptions though . Many oil filters are in a 'loss-side' of the pressurized oil flow, whereas the oil that goes through it is just a small percentage of the oil that is sent by the pump into the lube galleys to service the engine . The cleanest-filtered oil then, is returned to the pan and has provided NO lube service in this design . The idea of partial flow is many-fold, but ideally the oil that goes to the filter is allowed to pass through slower and at a lower pressure than the usual rate that goes elsewhere . The reason for that is to not force the filter media to be so impinged that it loses it's ability to capture and retain any sediment and debris from the engine . In olden days, yes - oil filters were all full-flow and they were really very inefficient and subject to collapsing and being ripped by the heavy flow of pressurized oil, especially in cold starts when oil viscosity was much higher (thicker) and the element would just rip or totally collapse under the flow demand . Very soon on, it was learned that a partial flow filter was the best way to clean the oil - although at any moment it was not filtering ALL the oil . This was until filter media and designs could at least catch up with modern engines and designs . As far as the rest of the oil - well some is regulated via a spring and (either) a sleeve or a ball on a seat that would require being forced off the seat to dump the excess pressure back into the oil pan-reservoir . Note that the oil pressure is not regulated to then flow to the engine, it is regulated to drop the overall pressure in the whole system by taking the excess pressure out of the circuit, leaving a steady pressure . MANY modern engines use non-regulate oil pressure to certain areas inside the engine - those that do allow the camshaft journal(s) to restrict the oil flow to (ultimately) the main bearings after the cam has had it's allowance . Typically the engines that use the non-regulated-at-the-pump systems are overhead cam engines . The cam journals may have a flow-notch machined into them or the clearances are sufficient to allow controlled leakage, ultimately lowering the pressure to the crankshaft and it's bearing surfaces . NOTE: INSERT-type bearings cannot have ungodly amounts of oil pressure or flow to them! They will 'float' and then they spin in their journals and they die a rather inglorious death taking the crank and the block with them; hence most modern engines don't even use shell-type bearings any more . The crank rides directly on the block journals themselves, as the block IS the crankshaft bearing surface! So oil flow might be expressed like the following:: PRESSURE REGULATION STAGE= PUMP>>REGULATOR>>FILTER>>RETURN TO PAN (remember the regulator does it's job by dumping the excess oil back into the pan - not TO the bearings . There are a few different flow designs for the FILTER/REGULATOR STAGE, and like I said some are full-flow and others partially-flow the filter, most typically like this:: FILTER FLOW STAGE VERSION 1 = PUMP>>REGULATOR>>FILTER>>RETURNED TO PAN FILTER FLOW STAGE VERSION 2= PUMP>>FILTER>>FILTERED OIL RETURNED TO PAN>>THE REST OF THE OIL THEN GOES TO CAM JOURNAL(S)>>TO MAIN JOURNALS As far as the rings and pistons/cylinder walls - there MAY of MAY NOT be squirters shooting pressurized oil at the undersides of the pistons - but in all cases the oil that is slung off the rod and main bearings usually winds up getting tossed onto those cylinder surfaces to at least give them some oil for cooling and lubrication . Engines with Eutectic Alloy pistons will not usually shoot oil at the undersides of the pistons to keep from then washing away the heat of the pistons (to aid combustion) . On very few engines with Eutectic pistons, the rods themselves are rifle-drilled (a very expensive process) for an oil supply to the wrist pins at the top of the rods themselves . As far as oil starvation at start up on (either) a new filter or cold start, the full flow filters are returned to capacity very quickly and no damage is done . A partial flow filter does not so impinge any oil flow characteristics for the rest of the engine very much - that a fresh filter will cause any more than a glitch in the ultimate flow of the lubrication system at all . It is however suggested that the engine has just been shut down after getting to somewhat normal oil flow and pressure before the filter and oil get changed to allow the bearings to not sit for hours and drain down and run too dry for a few moments after start up though . Last point: (really!) - some engines like to have an anti-drainback valve in them to keep the filter charged to full for start up and keep the timing chain tensioners from going slack at a very bad time . Toyota 22-Series engine were notorious for this problem - that of the tensioners allowing the timing chain to clatter against the engine housing and break away some of the plastic guides for the timing chain . If one were to put a non-check valved filter on these engines, the noise was scary . If the engine had enough mileage on it, the possibility of the chain jumping timing was very good too . The reason? The timing chain tensioner required oil pressure to keep the chain tight . I do not currently know of any engines with Gilmer belts for the timing drive that require oil pressure to keep them at the correct tension .	SurferJoe46 (51)
1207165	2011-06-06 23:45:00	The permutations permitting pandemonium cycles are truly a work of wonder. Murphy knew this of course.	R2x1 (4628)
1207166	2011-06-07 00:16:00	the celica doesn't really need oil changes as it burns enough that topping it up essentially keeps the oil fresh! joking aside the oil filter and oil change on it are simple and can be done without a pit or a jack the supra on the other hand needs a pit and a screwdriver and tiny japanese hands to get to it let alone change it's oil filter - its that bad its a small wonder why there are hundreds of oil filter relocation kits available for it! - in that case i really don't have the way or means to do it myself so i take it down to oil changers with a nice angry Donaldson oil filter and some good oil and get it done there - sure it costs $40 or so but its done in 10 minutes and i dont come out looking like ive just done a complete engine overhaul LOL	MAC_H8ER (5897)
1207167	2011-06-07 00:38:00	Surely it depends on Kms travelled as to how often you change the oil? Since the last two WOFs on carjam my car averages around 5 Km per day. If we change the oil every 10,000Km then that's once every 5.48 years roughly.	Snorkbox (15764)
1207168	2011-06-07 00:58:00	Surely it depends on Kms travelled as to how often you change the oil? Since the last two WOFs on carjam my car averages around 5 Km per day. If we change the oil every 10,000Km then that's once every 5.48 years roughly. it sure does it also depends on kms traveled in one journey as well your car doing 5km a day will most likley never get warm and the engine will be running cold constantly - running rich as a result - now doing this every day for months results in the oil degrading just as fast and just as bad as a car that's traveling a lot - you might only do 1000km in 6 months but the oil will be just as degraded and contaminated as a car that does 10,000km in 2 months my celica gets an oil change every 2000 or 2500km - about 4-6 months of travel - by then the oil really does need a change as its been ran cold all the time and the engine running rich has resulted in petrol washing into the oil essentially cancelling the effects of the oil that and im a nut that likes to over service his vehicles :P	MAC_H8ER (5897)
1207169	2011-06-07 01:23:00	.......then there is condensation inside the engine with lots of short runs causing emulsification of the oil. Removing and looking at the filler cap will show if there is oil/water emulsion. My wifes car does around 2000km a year with lots of short runs to the shops. However, I admit that whilst the oil is only changed every other year I do check on how it looks. It is only a 1000cc engine, so it does warm up fairly quickly.	Terry Porritt (14)
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