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Had the death rattle on start up. Changed oil and filter, Castrol 10/40 Magnetec. Initially the result was better but it has returned, especially noticable if i leave the car unused for a few days. Not sure if its also related to the weather i.e its getting colder in the mornings. Would it be better to go 5/30? In reality the issue seems to be not just how fast the oil can get around the engine on startup but what oil has remained in place to help protect before the oil has had a chance to get everywhere.

I doubt that the oil viscosity will make any difference. For anyone to make a fault diagnosis you will need more info. Rattling on start up may be valve lifters or bearings and maybe also nothing to worry about. If rattling and knocking continue after start up be more concerned.

Its not so much a 'fault', it would seem that this is a very common issue certainly on the NA model. I will see if i can find some other threads on this.

Try a search on "hla".

if changing oil viscosity doesn't work, here's a way to possibly cure hla noise from the big forum: http://www.miata.net/garage/hla/cleaning.html

I've done the HLA cleaning trick. Frankly it doesn't work as well as a good oil. In terms of both HLA noise and general lube performance I found that Castrol Edge 5W30, Royal Purple and Castrol German were all equally good, Amsoil 10w40 is brilliant, Mobil1 was pretty average and Magnatech is the worst oil I've used.

Good to know Phil - had read the article a while ago & thought it was a lot of effort to go to, except perhaps when rebuilding an extremely high km motor which exhibited the problem before hand.

thanks, will drop the Magnatec and try those other suggestions and let you know

For what it's worth,my NA rattled like buggery on start up,changed to Lubrimax M1 10W40,no more rattles.
WASP

When anyone here suggests one oil over another for a daily car I and perhaps others would be pleased to see what criteria/ observations and facts they have to support a view point. It is like the petrol debate. I put 95ron any "brand" without ever noticing any difference in power or economy and few people check each tankful . Your average MX5 pushing 250K and more could have used any brand of oil and not always changed at the recommended service level- who admits that they do not service their cars.

Mr M, you're lucky in having an NB with solid lifters as opposed to those of us with an NA & hydraulic lifters! I think you'll find Manga's recommendation is based in part at least on not experiencing hydraulic lifter noise in his NA8 when using the oils he recommends, as opposed to experiencing it with those he doesn't.

Motul Turbolite 10w40 & Castrol GTX3 15w40 both had some HLA cold rattles in my car. Solved by going to aussie made Gulf Western Premium Gold 15w40.

Using Nulon 5W30, started getting HLA noise on cold start up at about 10k km(about a years use) New filter and oil, noise gone...I figured the noise was a sign that the oil had finally done its dash
MB