Isuzu 3.1L 4JG2T... will Syn 5W40 work?

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Mar 27, 2011
Hi-- First post, so let's see how it goes. ;^) I've read Bob's FAQ on oil which required me to toss out most of the info I learned as a youth in late 70s / early 80s. My key take away is that modern oils don't have the problems of the early multigrade 10W40 stuff from the 80s. Most of the modern concern seems to be from oid being too thick at startup but the thinkness seems to be fine at operating temp. I've now got my first diesel, an used Isuzu 4JG2 3.1 TD with indirect injection out of a Japanese market Isuzu Bighorn (like a Trooper). It's installed in a 1995 Range Rover with an auto. The engine manual states that the recommended grade of oil is 15W40, usless you are using Isuzu branded oil and then 10W30 is an option. I'd like to use an synthetic, so I can run a longer OCI, but can't seem to find a 15W40 version with CJ-4 rating. Did I miss an option? Will the 5W40 like the Delo 400 Syn work? The local Bi-Mart has it for basically $20 a gallon on sale now. All feedback appreciated. smile Thanks, Ron
Welcome to BITOG! You certainly don't need a CJ4. Does the engine manual specify a "C" rating like CF4, CG4 or CH4? If you are on the Oregon coast or the Willamette Valley any good 15W40 will do unless the owner's manual is particular (same Japanese diesel are like that). East of the Cascades a 5W40 would be very good in the winter. There are a few CI4+ 5W40s left, but not a lot. There is an excellent 0W40 CI4+ in Canada: Co-Op D-MO SL if you anticipate really cold weather. You certainly don't NEED a CJ4 oil but I don't believe it would hurt the engine in any way and there are many CJ4 choices in the US. Charlie
Thanks! I made the assumption that CJ-4 was the current spec for modern deisel... maybe I shouldn't have. (sigh The specs from the manual: LUBRICATION MAKE BRAND / TYPE GRADE API ACEA ----------------------------------------------------------------- ISUZU GENUINE BESCO MULTI – Z TYPE CE (10W-30) CE ISUZU GENUINE BESCO MULTI – Z (10W-30) CD ISUZU GENUINE BESCO MULTI – Z SUV (5W-30) CD ISUZU GENUINE BESCO S – 3 (10W, 20W, 30, 40) CD EXXON / ESSO ESSOLUBE XD-3+ (15W-40) CG4/CF E2/B2 EXXON / ESSO ESSOLUBE XT331 (15W-40) CG-4/CF E2/B2 MOBIL DELVAC HP (15W-40, 20, 30, 40) CF/CE CALTEX / CHEVRON DELO CXJ (15W-40, 30, 40) CF SHELL RIMURA D (15W-40, 30, 40 CD/CF ELF PERFORMANCE TROPHY (15W-40) CE E3 TOTAL RUBIA XT (15W-40) CF-4 E2
The implication is that "modern" oils e.g. CG4 are OK. Therefore, followoing that logic, a CI4+ or CJ4 should work OK. There might be some controversy since it is a Japanese engine. I would make the decision about the viscosity based on climatic influences. Charlie
For normal OCIs any CJ-4 15w-40 dino will work. There are scores of UOAs now to show that any of the major brand name fluids do quite well. Seeing such a wide spread of recommended fluids (15w-40, 30, 40, etc) I'd say about any HDEO will work. If you don't like the idea of 15w-40, consider a dino or semi-syn in 10w-30. He did state, however, that he wanted to do longer OCIs. Therefore a syn could be a reasonable option. To know if the option of using syn is viable cost wise, you'll have to sit down and analyze all your costs including oil, UOAs (a must with longer OCIs), filters, etc, and contrast that to a "typical" dino OCI. If you cannot, or will not, utilize a syn long enough, they cannot pay for themselves and end up being a waste of money. $20/gallon for the syn you mentioned is a good price for sure. Still, you'd have to use it for some period longer (2x or 3x?) to get your money's worth.
OK... so I should just stick with the dino 15W40 and keep the oil changes to 5K or so. BTW, I'm using a K&N premium filter so that should not be the weak link... I hope. I appreciate all the advice!
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Any "normal" filter is going to do a fine job as well over such as moderate OCI (5k miles). The concept of waste on syn's can be also applied to overly expensive filters. Yes, the K&N is a great product, as is the M1, PureOne and others. But for 5k miles, it really isn't going to matter much at all. High end filters do a great job. But you're not tasking them much if your plan is 5k miles. Any decent brand name will suffice here as well. I'd agree that "better" filters do help bring down contamination loads, but the REAL controlling factor in such as short OCI is the oil additive package. It keeps most of the particulate at or below a few um in size, and that is far smaller than any traditional full flow filter is going to reach.
The 4JG2T normally has a dual full flow/bypass filter here,but in the US probably not. We try to change the oil at 5,00km and filter at 10,000km with any HDEO 15/40- but now they are getting old and worn out most of the ones I see don't get oil changes at all. They are a tough motor and hard to kill - but what does them in is over heating,it will crack the head.
CG-4 oils were a no-no in Japanese light diesels, most of that vintage spec CF-4 oils only or specific 3000+PPM calcium level oils but I've found CI-4, CI-4+ oils work very well in them. I'm currently running a low SAPS (1.05%) ACEA E-4,6,7 oil in a Nissan TD42T engine but don't have any UOA's to show yet. BTW, the 4JG2 would be a good conversion in the Rangie. Land Rover in Oz installed the big 4BD1 and 4BD1T engines in the 110 here in the mid-late eighties (all the Oz army Land Rovers run these engines) and later 300Tdi Defenders are sometimes converted back to Isuzu spec as the engines take a lot of modifying safely.
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