Not as good as I hoped
I have recently used 20w-50 semi-synthetis Diesel oil and found it simply cannot maintain its quality over time. I was an engine reconditioner for 20 years and always found that cars regularly serviced with Penrite oils to be extremely clean when I pulled the engines down. This may be due to high detergents in the oil. In terms of my engine, Patrol Z30 diesel, I found initial driving to be good up to almost 5000 but then valve train noises increased and the oil did not maintain its viscosity. It deteriorated to quite thin, has a slight odour and engine has starting burning oil which it has never done previously. Quality oils these days are often good for 10 000 but this oil did not even make 5000. I will return to my previous oil for this engine which is becomming hard to get (hence the change). The Valvoline durablend semi-sythetic 10w-40 is excellent for this particular engine as seen by many reviews. Perhaps the penrite oils are good for small petrol engines but definitely not for diesels. Its a pity because I do want to support Australian companies.
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