Contrary to what my good friend, Rob R. alludes, NEVER use a GL-5 Spec oil in an antique or
(age-ed) classic car. (and some cars built on into the '70’s!!)
There is “stuff” in the GL-5 Spec that, literally “eats” “yellow metals” (also called "Red Metals)… Basically ANYTHING with a copper/bronze based metal!!
I had a “lovely experience” a couple of decades ago… unknowingly, I started topping-up my '70 Datsun 510’s steering box up with a GL-5 spec oil…after a period of time, I “lost” my steering while doing “near eighty” in a right-left-right “S” curve… HAD to throw that pair of underwear away!!
I took that steering box apart and found the lower bearing race (originally solid bronze) looked like it had been “stewed” in acid!! (the ball bearings came loose, locking-up the steering!!) The top bearing race was “well eaten”, tho it still retained the ball bearings, it wasn’t long for the world!!
Since then, I took any and all GL-5 Spec oil in my shop to the recycle station and will go WAY outta my way to buy ONLY GL-4 Spec OIl!!
With respect to engine oil… I’m a Castrol freak, BUT USA Made Castrol Oil is NOT the same as The Castrol that SHOULD be used in our XK’s!! aka UK made Castrol!!
The UK Made Castrol HAS ZDDP!! USA Made Castrol DOES NOT have the ZDDP! This statement is true of a LOT of US made/US-Based Engine Oils… BEWARE!! The “option” is, of course, just add a 4oz bottle of ZDDP to every 4/5 quart oil change (I’d add THREE 4oz Bottles to an XK120’s nearly fifteen quart oil change!! IF you use any “modern” engine oil in a Jaguar XK120!!)
Bottom Line!! The Factory Jaguar XK120/MKVII Service Manual tells you EXACTLY what “spec” lubricants to use as well as when to change them… READ AND HEED!!! Newer is NOT Better!!
Charles Ch # 677556.
This has got me worried! I put Millers Hypoid 90 GL-5 in my freshly rebuilt ENV axle recently. Should I drain it and change it, Charles?
axles, I’d use GL4–75-90 or 90. gearboxes: 30 wt non synthetic engine oil-less or non detergent (no combustion by products in gearboxes…and if too slippery the synchros don’t work fast enough), engine oil…Castrol does make a “classic” with zddp, as do others, Mobil 1 has sufficient zddp ONLY in certain of the oil weights…not all, see their chart…the 15 50 has the right amount (1000 to 1400 ppm): the lower the ratio of weight (10-40 is 4-1; 15-50 about 3-1; 20-40 is -1:) the better…10-40 being the worst, 10 30 ok but not heavy enough for some older engines. Synthetic engine oil is fine…if it has zddp either in it or added…some say it finds small leaks …maybe, maybe not…but horror stories? no. The most important thing with engine oils is to have zddp 1000-1400ppm, and to have clean oil, change often. Shear, Heat and combustion by products destroy the oil structure. I know, it’s a dozen or so quarts…and a pain to change the filter, but enjoy fresh oil in your engine that costs $12K to rebuild.
for recent post from Dave, .I doubt bad fuel…just add some fresh. 91 octane should be enough…except maybe on the hottest days, hot engine temps, but if pings then adjust timing for it a little. Running on could be too rich which causes hot carbon in the cyl, or…what spark plug are you using? Recheck timing…a little too much advance causes issues…a little to little advance causes no issues. But also check timing when running…are centrifugal advances working, is vac unit working. Look for total, all in, in the mid 30s at 2500 to 3000 rpm. Nick
Hi Chris…an extract from an oil supplier re gl4/5…always best to follow the Jag spec for oil requirements. …The main difference between GL-4 and GL-5 gear oils is the amount of EP additives. Sulphur/Phosphorus containing products are used as EP-additive. This additive has the purpose to prevent the occurrence of micro-welds on the gear flanks at the local high temperatures which prevail in EP circumstances (temperatures well in excess of 800℃!) GL-5 has roughly twice the amount of EP additives compared to GL-4, which is why it is often used in high-pressure circumstances such as in a front axle and rear axle differential.
Sulphur/Phosphorus additives however have an unfavourable property: they can react aggressively towards bronze and copper. This can be disastrous for the synchromesh rings of a gearbox. Therefore it is not recommended to use GL-5 in a gearbox unless the manufacturer allows this.
Do the rear axles have any brass in them? I somehow thought they did not.
I think not…but it reinforces the point to not try to be to clever with oil and additives…just stick to “old school” and the spec in the Jag service manual…Steve
I took one of these apart not so long ago. I remember the shims/ cupped thrust washers (4) identified as #21 being bronze but can’t remember if #20 was too.
Diesel engines have a harder life. Much higher compression, high torque, knocking, stronger parts, more soot. I came to the conclusion that if anything, Diesel engine oil is a lot better for our engines. 10W30 is a thin oil, I don’t see why one would use it. If it leaks, thicker oil helps. If your oil pressure is fine you will be happy with a 10 or 15w40, or 20W50. I stick to industry oil in larger containers, nothing oriented towards careful and well situated classic car owners (but I admit to liking the retro containers).
Chris L;
Dig-out the Service Manual and see if it tells you IF there is any “brass.copper” metal
used in the Jag’s ENV Axle. The GL-5 Spec is NOT “friendly” to copper/brass (aka “Red/Yellow metals”).
Complements to MGCJAG for “hitting the (GL4/5) issue square on the head”!!
Charles Ch # 677556.
I’ll ask Geoff Holman if there’s any brass/bronze in the diff. I used Millers 90 Hypoid GL5. I’ve done a bit of research just now, and several articles said that most GL5 gear oils are safe for yellow metals nowadays, as the sulphur compound has been removed from modern formulas. I also noticed people say that it would only become a problem over 100 degs C, one saying 300 degs! How hot do diffs get in normal use? - I just don’t know…
Why rely on what others say…5mins to drain…5mins to flush and refill…cost £20…Steve
Thanks Nick, I’ll make another pass through the dizzy and carbs… Both just rebuilt. I’m thinking the dizzy advance is working due to the fact that when I rev the engine with the timing light on a mark I put on the starter gear, the mark advances solidly… Haven’t actually measured the degrees of advance. The spark plugs are the ones that were in the engine when I took over stewardship, I have pulled and cleaned them and checked the gap, maybe I’ll replace them… Not sure what ones they are. I guess I should start by pulling them, check the make/model, and look at their condition after about the 200kms I’ve put on since cleaning them and rebuilding the carbs, will certainly tell me how well I set up the carbs, maybe I’m just running rich and the timing needs some tweaking!?
I’d just replace plugs and eliminate them…sometimes there is a bad one…I have had that happen…then it is chasing gremlins…Nick
I don’t recall seeing any brass in a Salisbury axle.
Just spoke with Geoff, and he doesn’t recall any yellow metal in the XK’s ENV diff, though he has seen brass/bronze #21 cup washers in Mk V diffs (some Mk Vs did use the ENV). Anyway, he said that even if there was yellow metal in there it would take years for any erosion to take place. The advice was, run it for a while, then drain and change the oil to GL4. No need for panic!!
