mrfixer

Your car appears to be a CVT auto. In which case the transmission would appear to be slipping (the engine rpm is fluctuating widely, but the road speed is not changing much). A slipping CVT will quickly destroy itself so I would take it to a dealer ASAP.

I think this is the 3ZZFE engine. No EGR. High idle is caused by additional air going into the engine - check.. 1. Sticking throttle/idle speed control valve. 2. Split vacuum hose or leaking gasket on intake manifold, allowing air in. 3. Idle speed setting been lost due to battery disconnected (look on YouTube for how to relearn idle on Toyota).

non-DPF will be fine on C1, C2, C3.

Diesel engines suffer with sooting of the oil due to blowby. The soot is fine black particles less than 1 micron in size. Its important to keep the soot particles in suspension in the oil so that they don't accumulate and cause damage and blockages. For that reason dispersants are added to the oil. Black oil is a good thing because it means the dispersants are working and the soot will be carried out at the oil change. A good clean of the sump will mean your new oil stays clear a bit longer - but it will go black again in time.

The ECU will command the engine rpm to increase if there is additional load... e.g. additional electrical load or low battery voltage, air con, power steering..

Bad or disconnected sensor.

Better they are too slack than too tight. Although a bit clattery it doesn't normally make much difference to the running of the engine unless that are WAY out. Going up a grade in oil may quieten them (5W40 or 10W40).

I remember Japanese cars arriving in the early '70s with door mirrors so I doubt its an EU thing. Door mirrors are much more useful than wing mirrors.

From what I've heard, the fault arises either due to failure of the soldered joints on the controller PCB or failure of a sensor within the unit. If you can remove the controller then a competent electronics technician could reflow the joints.

Definitely too high. Overcharged most likely, but need to look at low side pressures and general operation to be able to diagnose. Don't leave it......

The kinematic viscosity of a 0w20 at 100deg.C. is about 9cSt. A 5W30 is about 10cSt. Its sweet FA difference to be honest. Anything up to a 40 would be ok. KV is non-linear with temp and increases massively at low temps. Around 0deg.C. can be 800+ cSt. so its important to run a 0W or a 5W for winter cold starts - ensures the oil gets round quickly. Important on Toyotas because they tend to run with a high fast idle - i.e. revs can jump to 2000rpm on a cold start.

I have spent half a lifetime in the motor industry and I can tell you that engine failures due to lubrication breakdown are almost unheard of nowadays. Obviously you need to maintain the oil level and change at least annually to avoid sludge (which is a problem on some engines). In Thailand I run a 1999 Camry 2.2. It has spent hours crawling in Bangkok traffic with the outside temp at 40+ deg and then blasting along highways at 70-80mph. The car now has 400 000 km on the original engine and still doesn't use any significant amount of oil. Its had a change every 6 months using the cheapest 5W-30 oil and a no-name filter from B-Quik (a local fast-fit chain). Just change the oil regularly and don't worry too much.

ECP and CP4L are now owned by LKQ Corp (a big US corporation) - some of their pricing is just crazy.

Change yearly. Any 5W-30 or 0w-20 (fully or semi-synth) will be just fine. Just make sure its SL or SM or SN spec. The brand doesn't matter so long as it meets the spec.

If you can afford to have the car laid up for a few days you might want to send the unit to one of the ECU repairers (e.g. BBA Reman, ECUtesting etc). Might be a relatively cheap fix and no coding required.