oil weight and oil pumps (1 Viewer)

[RedJed78]

Quick question. I know some aussies run 20w50 in their LC's and here in america we run , or supposed to run 5w30. I know there is an extreme temperature difference between Australia and United States or in my case Seattle. what is the difference between Aussie 1fefz oil pumps and American? is there a difference? my first instinct is the thicker oil would wear out the oil pump quicker and blow out main seals and such.
so if i replaced my 1fzfe on my 1997 LC, could it handle 20w50 or 10w40 without blowing out main seals, or wearing on the oil pump and causing a premature failure?

TIA, RJ78

 

[landtoy80]

I have no idea if there is a difference in oil pump but the US uses the lower viscosity oil to comply with CAFA standards. There is no "Energy Conserving" 20w50 oil. I dont think there is a Energy Conserving 10w40 oil?

I use 10w40 and 5w40 with oil additives so they are more likely 15w50 or 10w50 oils, dont that for over 60,000+ mi with no problem and have used 5w40 Rotella T6 diesel oil for over 200,000 mi.

Here is the non USA oil viscosity oil chart.

 

[DSRTRDR]

I use 20W50 in all of the cruisers, and even in the Miata

 

[mmml4]

Oil pressure has little to do with your main seals, they are not there to hold oil pressure. I would run the 20w50 with no worries.

 

[bloc]

All of the oil pump and front cover part numbers are the same for a 94 land cruiser with the 1FZ-FE, whether sold in North America, or Australia.

So no, there is no difference in the engines. Wouldn't make sense anyway if you think about it.. why make two different parts for the "same" engine just to run different oil viscosities?

Toyota put a pressure relief valve immediately after the oil pump itself so it is very unlikely for any seals in the system to see too much pressure, regardless of how thick or cold the oil is. Even then, as @mmml4 mentioned it isn't the main seals that would fail.. they basically only seal oil splashing and slight crank case pressure or vacuum that has nothing to do with oil pressure. Most likely culprit in the hypothetical of an overpressured oil galley system would be the front cover to block seal, the oil cooler seals, maybe the head gasket.. I'm most likely forgetting something. Either way, all of this stuff is downstream of the pressure relief valve so it is extremely unlikely for all of it to see too much pressure.

Like someone else mentioned.. it may have to do with fuel efficiency standards.. ambient temperature ranges, etc.

Modern synthetics can reliably run a larger viscosity spread (better protecting cold starts but not thinning out too much when the oil is warm or hot) and usually run extended drain intervals.. whether or not these benefits are worth the increased investment is the topic of MANY overly-beaten-dead-horse debates and frankly comes down to a personal decision for each car owner. Unless of course they are specified by the manufacturer.. which isn't the case for us. I run 0w-40 Mobil 1 synthetic.. at 100C it is on the thin side for a 40wt but can easily handle my summer activities of 100f+ here at home, then driving up to the mountains where it may get to freezing at night. Realistically I'd probably be fine with a conventional 5w-30 but like I said.. personal choice. I'm not hurting for cash and personally believe this synthetic is worth the money.


Anyway.. hopefully this helps. I think you are worrying too much about it.

 

[86tuning]

I've been using toyota 0w20 in my 80 for years. I do the normal 5-8k oil change intervals and have had no issues. Oil pressure sits in the middle normally and just past that when cruising. Oil consumption isn't an issue. My truck is at 90k miles now. Yes, I'm in Canada, but our climate is mild like Seattle.

Yes, the north american spec oil is 5w30 but if you're using mobil1 oil it's more like a 3w25 so 0w20 isn't that far off. Yes the Oz spec is 20w50 but they tend to be hard on their machinery.

Any particular reason you want to run a heavy weight oil? Is your truck high mileage, do you have oil consumption issues or oil pressure gauge issues?

 

[Dave 2000]

The viscosity changes are primarily for temperature. If the oil is too thick for example a 20/50 in the middle of a bitter winter, the oil pump will be unable to pull the thick oil through the strainer, or more correctly unable to pull the full demand. The result is the engine is starved of oil during the first few minutes of starting, obviously not good. During the first minute or so the oil pump will not suffer, it has oil in there from the previous period of running. As per bloc's comments, there are no seals actually exposed to pressure, the crank seals are more splash fed than pressure fed. The head gasket is exposed to regulated pressure i.e. after the pressure relief valve, and these often leak at this area on the Land Rover 200 tdi engine, AFAIK not an issue with any Toyota engine.

In the past (20/50w days) engines were built with poorer tolerances, this resulted in lower oil pressures when hot, the volume is put there by the pump but, the pressure is the result of the resistance brought about by clearances in the engine, the principles in this case is the main and big end bearings. Engines did not last long compared to today's offerings, the tighter clearances and oil with viscosity 0/30 is the norm. Toyota engineering 20 plus years ago was good enough to use pretty much any oil on the market, my diesel for example is listed as using IIRC 5/30 in the UK, in Spain I use Repsol 10/40. Warm enough to stay fluid when cold, and offer protection when hot....very hot.

So, IMHO the viscosity is more about getting oil to all areas of the engine during cold starting, and then maintaining a viscosity which allows the pressure (brought about by clearances) to be maintained as the engine heats up.

Note, too heavy an oil will prevent hydraulic lifters from functioning correctly, but not an issue in this case.

regards

Dave

 

[Rice]

A couple added points ....

If a thick oil causes the pressure relief valve to open it means critical points are being starved. In addition, while owners focus much attention on pressure only it is important to also have a significant amount of flow .... a thick oil can cause a high pressure but still not flow well through areas of close tolerance. Oil is not just a lubricant, it is also the only means of removing heat from bearings. All this is to say keep the oil thin enough that it can still flow.

 

[Howard705]

As Landtoy said-Across the Globe they recommend given grades-(where their engines see severe service) and no govt regs (same govt that prevent us from getting the good engines/models) imported. That logic alone should be enough to use the worldwide recommendations. That said-when the engines are up to operating temps-they are all pretty much the same or warmer if you're running it hard in warm weather-the tstat sees that it is at a min temp. On internal clearances-I'll bet most of them are closer to .003" than .001" on bearings these days being hi mile. I'd rather see my engine closer to the hi range of the gauge during normal rpms-when it's warm it won't be too high. Being good engines 1FZs probably able to "tolerate" lower pressures-lower viscocities-lower qualities of oil. Not an engineer but I'm sure basics like number/size of bearings (area)/balance/rpm range/rod size/fuel controls/etc all figure into this.