aymad

Hello Guyz,

Thank you for reading out my post, I live in Dubai(Middle East) where temperature tends to rise between 45C-52C, I have been owning a 1996 LS400 for around 6 years, and I have got some problems regarding oil leaks, the engine runs beautiful and soundless, been very taken care off... Since my car is Canadian Specs with towing package, It has 450K Kilometers on the clock.. Timing Belt kit with all seals and water pump had been changed at 400K Kilometers

Since it is my first car and being a noob, I ran OEM Toyota Engine Oil, 20W-50 Conventional Oil.. Which ran perfect, never ran into any problems, never had oil leaks.
Until after sometime, I saw something called Synthetic Oil which provides better protection, mileage etc, I decided to put OEM Lexus 5W-40 Synthetic Engine Oil, I felt some drastic power, smooth idling, better mileage, but within 6-8month, oil starts to get leak from valve covers, camshaft seals, crankshaft seals, rear cam bearing etc..
I saw the timing belt, and it was on its way out so decided for a timing job, since timing has to come off while change cam and crank seals.. All oil leaks were gone, but now cam shaft seals starting to leak again, after around 50K Kilometers...

Is that normal or am i running thin oil which causes it to leak?
Keeping in mind that the summer temperature is very hot here.. Which oil should I run now?

spuds

Im not sure on weight but run a 'high mileage' oil.It has additives that will expand the seals and help with leaks.I also would go back to conventional oil as that has a proven track record for you.Thats my OPINION.

spuds

Bump for more advice for OP.

will77

bradland

THIS /\/\/\/\/\/\/\/\/\
10-30 is recommended for temps up to 38C. Based on your location I'd say go with a good high mileage 10-40.
20-50 seems a bit thick for a motor designed to use 5-30.

aymad

Thanks @spuds for boosting this forum,

@bradland, Thanks for the providing the oil weights, I might add up that I have got some friends, which are running with same oil leaks problem. Most of them are running Adnoc 10w40 semi-synthetic engine oil (Its not available globally, but its UAE Governmental Oil Company which has it covered on every gas station).




What i have found out, to protect the engine from excessive damage and in extremely hot climates.. 10w50 fully synthetic will be a good option.. Since 10W will be the weight at cold start, and 50 will provide the protection on +50C.. But you said 20w50 will be a little too thick for the motor designed to use 5w30... What do you think, Running a 10w50 Fully-Synthetic will prematurely damage the components inside the motor? My location temp reaches 45C-52C in summers.

spuds

I dont know where you are getting the 10w50 but castrol says 1990-1997 LS400 should use 10W40.It isnt ambient heat temp,its engine oil temp that matters as far as I understand it.And the cars cooling system controls that heat.Guys,correct me if Im wrong here.

Castrol is a big name,if they say 10w-40,its the right advice IMO.
http://www.datateck.com.au/lube/CastrolRetailNzl/

Shell says 10w-40 for Bahrain.
===================
https://www.popularmechanics.com/car...o/a53/1266801/

Higher Mileage Oil: Today's vehicles last longer, and if you like the idea of paying off the car and running the mileage well into six figures, you have another oil choice, those formulated for higher-mileage vehicles. Almost two-thirds of the vehicles on the road have more than 75,000 miles on the odometer. So the oil refiners have identified this as an area of customer interest, and have new oils they're recommending for these vehicles.

When your car or light truck/SUV is somewhat older and has considerably more mileage, you may notice a few oil stains on the garage floor. It's about this time that you need to add a quart more often than when the vehicle was new. Crankshaft seals may have hardened and lost their flexibility, so they leak (particularly at low temperatures) and may crack. The higher-mileage oils are formulated with seal conditioners that flow into the pores of the seals to restore their shape and increase their flexibility. In most cases, rubber seals are designed to swell just enough to stop leaks. But the oil refiners pick their "reswelling" ingredients carefully. Valvoline showed us the performance data of one good seal conditioner that swelled most seal materials, but actually reduced swelling of one type that tended to swell excessively from the ingredients found in some other engine oils.
======================
So the upshot? A High mileage formulated oil,is the best choice for our cars according to the sources.and conventional,not synthetic(As yours didnt leak with conventional oil and with synthetics it does)
=================
Aymad,you are driving a 20 year old car.It uses a lower spec oil than new cars because its just what its made to use.To treat it as a NEW BMW is a bad choice,they are far different vehicles.Had your car always run on synthetics,I would be fine continuing to use them,but since it hasnt,changing to a synthetic is just bad practice at your mileage,IMO.
Its well known switching to synthetics in a high mileage vehicle is just asking for leaks.

A good High Mileage formulation,conventional oil,10w40,changed regularly will make your LS400 happy in the desert.It works in the desert here where 100-115 F is certainly possible.

Some examples,note they all say HIGH MILEAGE on them. A Conventional oil of whatever quality brand you can get....for example....



semi-synthetic,MAYBE it will swell seals enough to allow this type of oil to work for you,in 10w-40




Bottom line,10w-40,HIGH MILEAGE.High Mileage,thats my only advice I can give,and when it comes to oil,everybody has an OPINION.Hope thats helpful.

dicer

My opinion. Synthetic is great if you start out right after break in, meaning still new engine and stuff, and especially on newer engines that are sort of designed for it. I don't know where the 96 falls, but personally I will not use it on a 90 to 92, nor for other older vehicles. Synthetic is supposed to be a smaller molecule and with the word small means it likes to come out of small areas better than mineral oil. As far as the viscosity I think you had it right the first time with 20W-50 in your climate even a straight 40 would be okay as long as you don't see temps in the low 40 degree or less. If it was a VVT that is way different and more fussy about the weight. There are oil temp charts you can use.

aymad

Thanks all for your input and helping me out..

Came across with one of the UCF20/21 Service manual which states to use 5w30 only in cold regions.



So left the 5w30..

Availability of high mileage oils are quite a issue here in this region, so decided to move to AISIN API SN 20W-50 Semi Synthetic Engine Oil, as it has half synthetic technology.. (dont know how good AISIN is in oil products)..



I was suprised to see after 2days of an oil change, oil leak stopped. and engine performance is as same as like before with using 10w40...

Once again, thanks to all for inputing your knowledge, and helping me out of this oil leak misery..

spuds

Good choice on semi syn.Congrats on fix!

aymad

I am just amazed on how it can be even possible, that an oil leak can be stopped by just changing the oil grade.
Can it be even possible? Cant believe until now..

Michael88

check the valve cover bolts torque. they use a rubber grommet that can shrink and lose torque. check the PCV valve is not stuck or capped off, sounds like inner block pressure to me.