Can Oil Cause This?

[craig V8 taffe]

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.

[TokyoTaxi]

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.

[RCEBNR]

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

Edited May 8, 2006 by RCEBNR

[craig V8 taffe]

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

[R33TOM]

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

[craig V8 taffe]

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