Oil circulation noise on start-up

[zrcg1]

SECTOR,

That's exactly what I thought, in fact i'd convinced the specialist it was something more serious.

If you can, get the wheel arch liner out and hold the filter after you've started the car. You'll soon know whats causing the noise........

 

[eddieterry]

I would not worry as the noise is most likely to be the cold oil moving through the byepass holes in the thermostat unit. There are small byepass holes in the thermostat unit preventing a completely closed pressure system and some minute flow but the holes are small and thick oil gurgles through them - so some gurgling is noticeable until the oil is warmer and thinner and the thermostat starts to open. The noise is more noticable with a higher viscosity oil like Castrol Magnatec 10w - 40 semi (although many of the top engineers (Baz Hartech etc) now agree that a semi such as this is better used in the 993 than a fully synthetic such as Mobil 1 - still a contentious issue with some people though !!).
Eddie

 

[Johnny C]

Also, beware of overfilling it, as this can also do damage, causing plumes of white smoke to blow out the exhaust.

I overfilled my old 3.2 once - in Halfords car park where I couldn't really drain any excess off. The plume on the way to the nearest garage (about 300 yards) was tremendous, it completely obscured 2 lanes of the dual-carriageway and caused the mechanic much amusement

 

[Porker993]

I saw it happen once when a lady pulled into our local Shell station to top up her oil level, in a white 3.2. While I was filling up the 993, she set off amidst a truly spectacular cloud of white smoke. I couldn't believe what had just happened - people should have to go on a course before being let loose in these cars.

 

[sue11sam]

I fully agree about the use of semi synth on your 993 engine , the small savings using this oil cannot outweigh the potential risk !! IMOH

My engine tends to gurgle more on cool down on tickover after a run!!

 

[eddieterry]

It is not the cost that is the issue it is the high temperature in the AirCooled engine which can cause problems with particular oil components in some fully synthetic oils.

 

[sue11sam]

Really ? are we talking specifically , about all aircooled four stroke engines or only Porsche flat 6 ? what about operating temps on 2 stroke motors , which are far higher , aircooled aero motors ? I would like to see the data , I would agree that a greater weight synth seems to suit the motor as it becomes worn , certainly suits mine although I am using a Motul fully synth .

 

[eddieterry]

A number of top engineers including Baz Hartech would argue with you Maurice and will simply say that a good quality (recognised name) semi synthetic 10-40 will suit the 993 and other Air / Oil cooled 911 and provide the best all round protection.
They back this up with technical reasons but this would only lead to arguments and will not change their conclusion which is based on what they find out through experience - especially when the experienced voice doesn't actually know why they proved that was best - just that it was! - Only replying as I am interested in the whole debate about this and have researched it quite thoroughly.
Eddie
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[sue11sam]

Well , they are entitled to their opinion , but in the absence of any data to suport it , I would tend to go with the majority of experts and Porsche who almost all would go with the synth . I have been using synth in my performance engines since 1984 , where on turbo engines the heat generated is far higher than on any nat asp unit , and synth is the only oil to handle those temps , giving excellent lube life , up to twice the mineral life , but would change the filter at half oil life.

My background incidently is Very high output internal combustion , reciprocating engines and turbines of all types , and only 40 years experience !!

 

[eddieterry]

Sorry to get the formatting wrong Maurice (bit new to this) and take your points. I am just quite interested that the people who actually rebuild engines (such as Hartech - who have one of the best reputations in this field) feel that semi - synthetic oil seems to cause less wear than certain fully synthetic oils. I have always been an advocate of fully synthetic oils (always using Mobil 1 5W - 40 ) until hearing this directly from Baz and also a number of other independant garages. At first I thought it was just the cost or worries about the very thin cold viscosity finding leaks but they all commented that it was the wear they were worried about.
I would always go with N rated tyres but now not so sure about certain makes of fully synthetic oils (some fully synthetics do not have the problem apparently). I like to change the oil and two filters myself in April and then agian in November as I do not do a very high mileage but do want use what is best for the engine which is why I asked for advice from those who I thought would know and would not have any commercial reason to give me poor advice (they could of course be wrong).

 

[sue11sam]

I beleive you are correct in your statement concerning some synth oils , in my opinion there are differences , and some synths are a higher spec than others . Some of the very well established oils are not always the best performers , but usually the most expensive ! Also worth looking at your lube weight as the engine wears IMO .

 

[eddieterry]

Opie Oils agree with you about that - they give good technical reasons why they advise oils such as Silkolene Pro S 5W-40 rather than the usual one in many of their advice threads on places like Pistonheads. I would be interested to know what weight you think is best for a standard 993 engine as it gets older ?
Eddie