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Hey guys, i own a 98 r34 gt-t tiptronic with 85K klms.

Recently i changed my oil and oil filter and pretty much the day after the car idles rough and is also noisier at idle - the smoothness of the week after an oil change wasn't there. I made the mistake of using cheap oil - Caltex Havoline or something (10w - 30).

Also the oil pressure reading at idle is slighter lower than normal. Usually it reads 2 but now it reads like 1.7 or something.

Can the cheaper oil do this or maybe i moved some wire or connection while removing the old oil filter? Are there any important leads down there?

ANy help would be great - thanks.

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In my opinion ( & experience ) oil CAN make a difference in the idle and performance of the engine. Not a huge difference but a noticeable one.

I've been using Pennzoil Full Synthetic 5W-50 for the last couple of years and last weekend I did an oil + filter change and put Genuine NISSAN Special Blend 7.5W-30 in ( much cheaper ) and as I was pouring it in, I noticed just how thin ( water like ) the oil was. I can now notice a difference in idle, engine noise and oil pressure ( and it's NOT my imagination ).

I'm actually going this arvo to get some more Pennzoil and I'll change it back before this weekend. Paranoid ?!?! Maybe......... But I've got a fully re-built engine that I'm not willing to gamble on. :P

did u check u didnt overfill too? when i bought my car it had a rough idle and hesitation when cold. i did al the fluids and had abt 1.5l too much oil in it from the4 previous owner

The manual states 5.3 L for an RB25DET with an oil filter change. I put in about 5.5L. Is this too much? I'll try draining some. It does read at the top on the dipstick.

Also when driving it's more rough at 1500 - 2000rpm then it was with the old oil which had done 7000km, Castrol GTX3 btw (i think 15w 40).

Thanks for the feedback

drain that oil out now and put some good quality full synthetic oil in there,

Your need something of 5w30 or something similar to that,

motul turbolite, castrol magnatec a few brands to consider, dont buy cheap oil, your end up damaging your engine

Hey guys, there was too much oil - at the top of the disptick marking. The manual states 5.3L but i'm assumning this is with a full engine flush or something. I ended up draining some and getting it to around 4.5L - there's always some residual oil.

It idles normally now and sounds the same as it used to and the oil pressure reads the same as before, around 2 at idle. Unfortunately it's still rough while cruising round 1500-2000 rpm. Hopefully i havn't damaged it - i'll try changing to some better oil.

Thanks for the feedback guys

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