Fluctuating oil pressure.What does it mean?

Q. I’ve not long become the owner of a kitted out 100 Series LandCruiser. It’s got the 1HD-FTE factory turbo diesel engine and I’m very happy with performance. I’ve owned a few different 4WDs in my time, but I’ve noticed something odd with the oil pressure gauge on this one. Why on the 1HD-FTE engine, does the oil pressure fluctuate so much? My other vehicles oil pressure gauges never seemed to move much. To give you an idea of how much the oil pressure is fluctuating, it moves from a below one quarter on the gauge at idle, to only just over three quarters on the freeway. Is this normal for this engine, if not why is mine moving around so much? I hope I haven’t bought a lemon! Looking forward to hearing back from you soon.

A. That’s a bit of a standard thing. There are many potential reasons. If you are satisfied you are using the recommended engine oil by Toyota then all should be fine. By installing a mechanical gauge you may just allay your fears but in the end I haven’t heard or seen of a 1HD-FTE with regularly failing engine bearings. Without doing physical tests on it I can never diagnose 100% without seeing the vehicle. The pressure relief valve controlling oil pressure could (but very remotely) be sticky. Sure the 1HD-T engines had a heavily documented history of ‘Big End’ bearing failures but again the 1HD-FTE was clear of all that. I see the 1HD-FT and E engines come through our shop with 500,000km pretty regularly now and they’re still going strong.